Switchable hydrophilicity solvents and methods of use thereof

ABSTRACT

A solvent that reversibly converts from a hydrophobic liquid form to hydrophilic liquid form upon contact with water and a selected trigger, e.g., contact with CO 2 , is described. The hydrophilic liquid form is readily converted back to the hydrophobic liquid form and water. The hydrophobic liquid is an amidine or amine. The hydrophilic liquid form comprises an amidinium salt or an ammonium salt.

RELATED APPLICATIONS

This application claims the benefit of the filing date of U.S.Provisional Patent Application No. 61/255,623, filed on Oct. 28, 2009,Canadian Patent Application No. 2,683,660, filed on Oct. 28, 2009, andU.S. Provisional Patent Application No. 61/311,178, filed on Mar. 5,2010, the contents of which are incorporated herein by reference intheir entirety.

FIELD OF THE INVENTION

The field of the invention is solvents, and specifically solvents thatcan be reversibly converted between hydrophobic and hydrophilic forms.

BACKGROUND OF THE INVENTION

Conventional solvents have fixed physical properties which can lead tosignificant limitations in their use as media for reactions andseparations. Many chemical production processes involve multiplereactions and separation steps, and often the type of solvent that isoptimum for any one step is different from that which is optimum for thenext step. Thus it is common for the solvent to be removed after eachstep and a new solvent added in preparation for the next step. Thisremoval and replacement greatly adds to the economic cost andenvironmental impact of the overall process. Therefore, there exists aneed for a solvent that can change its physical properties.

Solvents are commonly used to dissolve material in manufacturing,cleaning, dyeing, extracting, and other processes. In order for asolvent to dissolve a material quickly, selectively, and in sufficientquantity, it is usually necessary for the solvent to have particularphysical properties. Examples of such properties include hydrophobicity,hydrophilicity, dielectric constant, polarizability, acidity, basicity,viscosity, volatility, hydrogen-bond donating ability, hydrogen-bondaccepting ability, and polarity. At some point in such a process afterthe dissolution, separation of the material from the solvent may bedesired. Such a separation can be expensive to achieve, especially ifthe solvent is removed by distillation, which requires the use of avolatile solvent, which can lead to significant vapor emission lossesand resulting environmental damage e.g., through smog formation.Furthermore, distillation requires a large input of energy. It wouldtherefore be desirable to find a non-distillative route for the removalof solvents from products. This is particularly difficult if the solventand the product are both very low in polarity.

US Patent Application Publication No. 2008/0058549 discloses a solventthat reversibly converts from a nonionic liquid mixture to an ionicliquid upon contact with a selected trigger, such as CO₂. The nonionicliquid mixture includes an amidine or guanidine or both, and water,alcohol or a combination thereof. However, that document does notprovide certain advantages of the present invention as described below.

SUMMARY OF THE INVENTION

In a first aspect, the invention provides a system comprising: means forproviding a switchable hydrophilicity solvent (SHS) that is awater-immiscible liquid; means for adding to the SHS an aqueous liquidto form a two-layer liquid mixture; means for exposing the two-layerliquid mixture to CO₂ in the presence of water thereby protonating theSHS to form protonated-SHS, which is water-miscible or water-soluble, sothat the two-layer liquid mixture forms a single-layer liquid mixture;and means for exposing the single-layer liquid mixture to (i) heat, (ii)a flushing gas, or (iii) heat and a flushing gas, thereby expelling CO₂from the single-layer liquid mixture which leads to deprotonation of theprotonated-SHS to form SHS so that the single-layer liquid mixture formsa two-layer liquid mixture; and optionally, means for separating aselected compound from the protonated-SHS prior to reformation of SHS.

In some embodiments the system further comprises means for isolating andtransporting each layer of the two layer liquid mixture for reuse. Insome embodiments, the aqueous liquid comprises salty water. In someembodiments, the means for exposing to heat comprises means for heatingto about 60° C. In some embodiments, the means for exposing to heatcomprises means for heating to about 80° C. In some embodiments, the SHScomprises a compound of formula (1), a compound of formula (10), or acombination thereof. In some embodiments, the SHS comprisesN-ethylpiperidine, N,N,N-triethylamine, N,N-diethyl-N-methylamine,N,N-dimethyl-N-cyclohexylamine, N,N-diethyl-N-cyclohexylamine,N,N-dimethyl-N-hexylamine, N,N-diethyl-N-butylamine,N,N-dipropyl-N-methylamine, N-butylpyrrolidine,N,N′-dipropyl-N,N′-diethylbutane-1,4-diamine,N1,N1,N4,N4-tetraethylbutane-1,4-diamine, or any combination thereof. Insome embodiments, the SHS comprises N,N-dimethyl-N-cyclohexylamine.

In a second aspect, the invention provides a system for removing ahydrophobic contaminant from a solid material, comprising: means forcontacting a mixture of solid material and hydrophobic contaminant witha liquid comprising a liquid switchable hydrophilicity solvent so thatat least a portion of the hydrophobic contaminant becomes associatedwith the liquid to form contaminated liquid; optionally, means forseparating the contaminated liquid from residual solid material; meansfor contacting the contaminated liquid with CO₂ in the presence of waterto convert a substantial amount of the switchable hydrophilicity solventfrom its unprotonated form to its protonated form, resulting in atwo-phase liquid mixture having a hydrophobic liquid phase comprisingthe hydrophobic contaminant, and an aqueous liquid phase; and means forseparating the hydrophobic liquid phase from the aqueous liquid phase.

In a third aspect, the invention provides a system for cleaning solidparticles that are contaminated by a hydrophobic compound, comprising:means for adding solid particles that are contaminated by a hydrophobiccontaminant to the system of the first aspect, wherein the hydrophobiccontaminant dissolves in the SHS; means for isolating particles that aresubstantially contaminant-free; and optionally, means for collecting thesubstantially pure contaminant that forms as a layer that is distinctfrom the single-layer liquid mixture comprising protonated-SHS andaqueous liquid.

In some embodiments of the second or third aspects, the solid particlesor solid material that are contaminated by a hydrophobic compoundcomprise oil sands, and the contaminant comprises bitumen. In someembodiments of the second or third aspects, the solid particles or solidmaterial that are contaminated by a hydrophobic compound comprisedrilling fines, and the contaminant comprises drilling fluid. In someembodiments of the second or third aspects, the solid particles or solidmaterial that are contaminated by a hydrophobic compound comprise soilcontaminated by hydrocarbons, and the contaminant compriseshydrocarbons. In some embodiments of the second or third aspects, thesolid particles or solid material that are contaminated by a hydrophobiccompound comprise plastic, and the contaminant comprises dirt. In someembodiments of the second or third aspects, the solid particles or solidmaterial that are contaminated by a hydrophobic compound compriseplastic, and the contaminant comprises an odorous compound. In someembodiments of the second or third aspects, the SHS comprises a compoundof formula (1), a compound of formula (10), or a combination of acompound of formula (1) and a compound of formula (10), wherein thecompound of formula (10) is N-ethylpiperidine, N,N,N-triethylamine,N,N-diethyl-N-methylamine, N,N-dimethyl-N-cyclohexylamine,N,N-diethyl-N-cyclohexylamine, N,N-dimethyl-N-hexylamine,N,N-diethyl-N-butylamine, N,N-dipropyl-N-methylamine,N-butylpyrrolidine, N,N′-dipropyl-N,N′-diethylbutane-1,4-diamine,N1,N1,N4,N4-tetraethylbutane-1,4-diamine, or any combination thereof.

In a fourth aspect, the invention provides a system for extracting aselected hydrophobic material from a solid, comprising: means for addingsolid particles that comprise a selected hydrophobic material to thesystem of the first aspect, wherein the hydrophobic material dissolvesin the SHS; means for isolating solid particles that are substantiallyfree of the selected hydrophobic material; and means for collecting thesubstantially pure selected hydrophobic material that forms as a layerthat is distinct from the single-layer liquid mixture comprisingprotonated-SHS and aqueous liquid.

In some embodiments of the fourth aspect, the solid is derived from aseed, nut, plant, algae, or bacterial organism. In some embodiments ofthe fourth aspect, the system further comprises means for masticatingthe solid prior to exposing it to SHS. In some embodiments of the fourthaspect, the selected hydrophobic material comprises: nut oil, algae oil,seed oil, vegetable oil, canola oil, soybean oil, or biopolymer. In someembodiments of the fourth aspect, the SHS comprises a compound offormula (1), a compound of formula (10), or a combination thereof. Insome embodiments of the fourth aspect, the SHS comprisesN-ethylpiperidine, N,N,N-triethylamine, N,N-diethyl-N-methylamine,N,N-dimethyl-N-cyclohexylamine, N,N-diethyl-N-cyclohexylamine,N,N-dimethyl-N-hexylamine, N,N-diethyl-N-butylamine,N,N-dipropyl-N-methylamine, N-butylpyrrolidine,N,N′-dipropyl-N,N′-diethylbutane-1,4-diamine,N1,N1,N4,N4-tetraethylbutane-1,4-diamine, or any combination thereof.

In a fifth aspect, the invention provides a system for isolation of acomponent in a chemical synthesis, comprising: means for adding reagentsof a chemical reaction to the system of the first aspect, wherein atleast one component of the chemical reaction dissolves in the SHS; andmeans for collecting the substantially pure component of the chemicalreaction that separates from the single-layer liquid mixture comprisingprotonated-SHS and aqueous liquid.

In some embodiments of the fifth aspect, the component of the chemicalreaction is a product of the chemical reaction. In some embodiments ofthe fifth aspect, the substantially pure component is a biodiesel. Insome embodiments of the fifth aspect, the SHS comprises a compound offormula (1), a compound of formula (10), or a combination thereof. Insome embodiments of the fifth aspect, the SHS comprisesN-ethylpiperidine, N,N,N-triethylamine, N,N-diethyl-N-methylamine,N,N-dimethyl-N-cyclohexylamine, N,N-diethyl-N-cyclohexylamine,N,N-dimethyl-N-hexylamine, N,N-diethyl-N-butylamine,N,N-dipropyl-N-methylamine, N-butylpyrrolidine,N,N′-dipropyl-N,N′-diethylbutane-1,4-diamine,N1,N1,N4,N4-tetraethylbutane-1,4-diamine, or any combination thereof.

In a sixth aspect, the invention provides a system for isolation of atleast one selected plastic from a mixture of plastics, comprising: meansfor adding to the system of claim 1 a mixture of plastics comprising atleast one plastic that is soluble in a switchable hydrophilicitysolvent; optionally, means for removal of undissolved plastics; andmeans for collecting the at least one plastic that precipitates from thesingle-layer liquid mixture comprising protonated-SHS and aqueousliquid. In some embodiments of the sixth aspect, the at least oneplastic that is soluble in a switchable hydrophilicity solvent comprisespolystyrene. In some embodiments of the sixth aspect, the SHS comprisesa compound of formula (1), a compound of formula (10), or a combinationthereof. In some embodiments of the sixth aspect, the SHS comprisesN-ethylpiperidine, N,N,N-triethylamine, N,N-diethyl-N-methylamine,N,N-dimethyl-N-cyclohexylamine, N,N-diethyl-N-cyclohexylamine,N,N-dimethyl-N-hexylamine, N,N-diethyl-N-butylamine,N,N-dipropyl-N-methylamine, N-butylpyrrolidine,N,N′-dipropyl-N,N′-diethylbutane-1,4-diamine,N1,N1,N4,N4-tetraethylbutane-1,4-diamine, or any combination thereof.

In a seventh aspect, the invention provides a system for adding ahydrophobic compound to a solid material, comprising: means for adding ahydrophobic compound to the system of the first aspect; and means foradding a solid material to the system of the first aspect such that thesolid material contacts the hydrophobic compound and become at leastpartially coated or impregnated by the hydrophobic compound; whereinafter exposure of the SHS to CO₂ and consequent migration ofprotonated-SHS to the aqueous layer, solid material that is at leastpartially coated or impregnated by the hydrophobic compound iscollected.

In some embodiments of the seventh aspect, the solid material is atextile and the hydrophobic compound is a dye. In some embodiments ofthe seventh aspect, the solid material is a textile and the hydrophobiccompound is a corrosion inhibitor. In some embodiments of the seventhaspect, the solid material is a vesicle. In some embodiments of theseventh aspect, the solid material is a polymer bead. In someembodiments of the seventh aspect, the hydrophobic compound is acorrosion inhibitor, surface stabilizer, mordant, preservative,antioxidant, enzyme, antigen, or brightener. In some embodiments of theseventh aspect, the solid material is suitable for use in drug deliveryand the hydrophobic compound is drug. In some embodiments of the seventhaspect, the SHS comprises a compound of formula (1), a compound offormula (10), or a combination thereof. In some embodiments of theseventh aspect, the SHS comprises N-ethylpiperidine,N,N,N-triethylamine, N,N-diethyl-N-methylamine,N,N-dimethyl-N-cyclohexylamine, N,N-diethyl-N-cyclohexylamine,N,N-dimethyl-N-hexylamine, N,N-diethyl-N-butylamine,N,N-dipropyl-N-methylamine, N-butylpyrrolidine,N,N′-dipropyl-N,N′-diethylbutane-1,4-diamine,N1,N1,N4,N4-tetraethylbutane-1,4-diamine, or any combination thereof.

In an eighth aspect, the invention provides a system for obtainingdissolved polymeric foam, comprising: means for contacting polymericfoam with a switchable hydrophilicity solvent so that the polymeric foamdissolves to form a liquid mixture; optionally, means for mixing theliquid mixture; and means for transporting the liquid mixture into aseparate vessel.

In some embodiments of the eighth aspect, the means for transferringcomprises a pump for pumping the liquid mixture into a separate vessel.In some embodiments of the eighth aspect, the system is portable. Insome embodiments of the eighth aspect, the portable system comprisesmeans for switching the SHS from its protonated hydrophilic form to itshydrophobic form. In some embodiments of the eighth aspect, the portablesystem further comprises means for switching the SHS from itshydrophobic liquid to its protonated hydrophilic form. In someembodiments of the eighth aspect, the polymeric foam is expandedpolystyrene, extruded polystyrene foam, polystyrene foam packing chips,Styrofoam™, rigid polystyrene foam, high impact thin polystyrene, orpolystyrene foam packing chips. In some embodiments of the eighthaspect, the SHS comprises a compound of formula (1), a compound offormula (10), or a combination thereof. In some embodiments of theeighth aspect, the SHS comprises N-ethylpiperidine, N,N,N-triethylamine,N,N-diethyl-N-methylamine, N,N-dimethyl-N-cyclohexylamine,N,N-diethyl-N-cyclohexylamine, N,N-dimethyl-N-hexylamine,N,N-diethyl-N-butylamine, N,N-dipropyl-N-methylamine,N-butylpyrrolidine, N,N′-dipropyl-N,N′-diethylbutane-1,4-diamine,N1,N1,N4,N4-tetraethylbutane-1,4-diamine, or any combination thereof.

In a ninth aspect the invention provides a method of obtaining a polymerfrom its source cells, comprising: contacting bacteria that haveproduced polymer, or a lysate of said bacteria, with a switchablehydrophilicity solvent in which the polymer dissolves, to form amixture; optionally removing solid debris from the mixture to form aliquid comprising the switchable hydrophilicity solvent and dissolvedpolymer; contacting the liquid with CO₂ in the presence of water toswitch the switchable hydrophilicity solvent to its hydrophilic form, inwhich the polymer is immiscible, to form a two phase liquid mixture; andcollecting the polymer.

In some embodiments of the ninth aspect, the polymer comprisespolyhydroxyalkanote. In some embodiments of the ninth aspect, thebacteria are Cupriavidus necator or Pseudomonas putida. In someembodiments of the ninth aspect, the SHS comprises a compound of formula(1), a compound of formula (10), or a combination thereof. In someembodiments of the ninth aspect, the SHS comprises N-ethylpiperidine,N,N,N-triethylamine, N,N-diethyl-N-methylamine,N,N-dimethyl-N-cyclohexylamine, N,N-diethyl-N-cyclohexylamine,N,N-dimethyl-N-hexylamine, N,N-diethyl-N-butylamine,N,N-dipropyl-N-methylamine, N-butylpyrrolidine,N,N′-dipropyl-N,N′-diethylbutane-1,4-diamine,N1,N1,N4,N4-tetraethylbutane-1,4-diamine, or any combination thereof.

In a first broad expression of the invention switchablehydrophilicity/hydrophobicity compounds and methods of preparing andusing such compounds are provided. The compounds are based on amidine oramine and switch between a hydrophobic form (amidine or amine) and ahydrophilic form which is a salt of the amidine or amine (amidinium saltor ammonium salt) in response to a selected trigger. The hydrophobicform is in a liquid state. When prepared as described hereinbelow, thehydrophilic form can be provided as an aqueous solution of a salt below100° C., e.g., at room temperature. The trigger to change fromhydrophobic form to hydrophilic form may be exposure of the amidine formto CO₂, CS₂, or COS. Given its convenience, CO₂ is especially preferred.The compounds of embodiments of the invention are not only switchable,but reversibly so, and removal of the trigger, e.g., removing CO₂,causes the hydrophilic form to switch to the hydrophobic form. Thehydrophobic form is sufficiently hydrophobic that is immiscible withwater and can separate from an aqueous mixture. The hydrophobic form canthus be easily separated from water by decanting. In their hydrophobicform, the compounds of the invention are sufficiently hydrophobic thatthey are miscible with or can dissolve other hydrophobic compounds andcan therefore be used as solvents.

In a second broad expression of the invention switchablehydrophilicity/hydrophobicity compounds and methods of preparing andusing such compounds are provided, where the compounds are based onamidine or amine and switch between a first hydrophobic form with nolocal charges and a second, hydrophilic ionic form in response to aselected trigger. The trigger to change from first form to second,hydrophilic form may be exposure of the first form to CO₂, CS₂, or COS.Given its convenience, CO₂ is especially preferred. The compoundsaccording to this aspect of the invention are not only switchable, butreversibly so, and removal of the trigger, e.g., removing CO₂, causesthe second, hydrophilic ionic form to switch to the first hydrophobicform. The hydrophobic form is sufficiently hydrophobic that it isimmiscible with water and will separate from an aqueous mixture.

It should be understood that it is appropriate for purposes of thepresent disclosure to call removal of a first trigger a “trigger”itself, in that it causes a change in properties of the compound inquestion.

Another broad expression of the invention provides a salt that forms ahydrophilic liquid with water wherein, the hydrophilic character of thissalt changes in response to a trigger such that it transforms into ahydrophobic liquid and water. Another broad expression of the inventionprovides a compound that is a hydrophobic liquid. The hydrophobic liquidchanges in response to a trigger in the presence of water such that itbecomes an aqueous hydrophilic liquid comprising a salt.

According to a tenth aspect, the invention provides a compound offormula (1):

that is water-immiscible; where R¹, R², R³, and R⁴ are independently H;a substituted or unsubstituted C₁ to C₁₀ alkyl group that is linear,branched, or cyclic; a substituted or unsubstituted C_(n)Si_(m) groupwhere n and m are independently a number from 0 to 10 and n+m is anumber from 1 to 10; a substituted or unsubstituted C₅ to C₁₀ arylgroup; or a substituted or unsubstituted heteroaryl group having from 4to 10 atoms in the aromatic ring.

The compound of formula (1) is an amidine. The compound of formula (1)is in a liquid state. By “liquid state” is meant that when the compoundis water saturated, at a temperature below 70° C., and at a pressure ofabout 1 atm, it is a liquid.

In some embodiments of the tenth aspect, R¹, R³, and R⁴ are nothydrogen. In certain embodiments of the tenth aspect, the total numberof carbon and/or silicon atoms in all substituents R¹, R², R³, and R⁴ isin the range of 10 to 20. In certain embodiments, two of the R groups informula (1), together with the amidine-nitrogen or amidine-carbon towhich they are attached, are joined and form a ring. In some alternativeexamples of this embodiment, R¹ is joined to R²; R¹ is joined to R³; R²is joined to R³; R³ is joined to R⁴. In other embodiments, two pairs ofR groups each form a ring.

In certain embodiments of the tenth aspect, a compound of formula (1)has a logP value in the range of about 3 to about 7. Compounds having alogP value of less than 3 may be too hydrophilic such that they may bemiscible with water. Consequently such liquids would be unsuitable forthe present invention because they would offer poor extraction ofhydrophobic compounds and could not be separated from water.

Compounds having a logP value of greater than 7 are less preferredbecause they are more hydrophobic in character such that the hydrophilicionic form may be less easily miscible with water. In addition, becausethe hydrophilic form may be a solid compound rather than an ionicliquid, the compounds could be unsuitable for use in the separationmethods described herein if they are not water-miscible.

In certain embodiments, the compound of formula (1) has a logP value inthe range of about 4.5 to about 6.5.

In certain embodiments of the tenth aspect, the compound of formula (1)is:

According to a further broad expression of the invention, a salt that isformed by the reaction of carbon dioxide with an amidine and water isprovided. This reaction is reversible, such that by removing the CO₂,the amidine and water are regenerated.

In an eleventh aspect, the invention provides a salt of formula (2)

where R¹, R², R³, and R⁴ are as defined in the tenth aspect, E is O, Sor a mixture of O and S, n is a number from 1 to 6 sufficient to balancecharge, that is water-soluble and that was prepared by a methodcomprising: contacting a compound of the tenth aspect with at least oneof CO₂, CS₂ or COS in the presence of water, thereby converting thecompound to the salt of formula (2). Optionally, any two of R¹, R², R³and R⁴, taken together with the atoms to which they are attached join toform a ring.

The anion ^(θ)E₃CH may thus be selected from the group comprising:⁻O₃CH, ⁻O₂SCH, ⁻OS₂CH, and ⁻S₃CH. It will be apparent that the use ofcarbon dioxide would provide anion ⁻O₃CH, while the use of CS₂ or COScould provide ⁻O₃CH, ⁻O₂SCH, ⁻OS₂CH, and ⁻S₃CH.

The ionic form of formula (2) is an amidinium salt. The ionic form offormula (2) reversibly converts to a compound of formula (1) of thetenth aspect and water when carbon dioxide, CS₂ or COS is removed, andthe compound of formula (1) of the tenth aspect converts to the ionicform of formula (2) upon contact with carbon dioxide, CS₂ or COS andwater. Carbon dioxide, CS₂ or COS may be removed by contacting the ionicform of formula (2) with a gas that contains substantially no carbondioxide, CS₂ or COS.

In some embodiments of the eleventh aspect, the total number of carbonand/or silicon atoms in all of R¹, R², R³, and R⁴ is in the range of 10to 20. In some embodiments of the eleventh aspect, the compound offormula (1) has a logP value in the range of about 3 to about 7. In someembodiments of the eleventh aspect, the logP value is in the range ofabout 4.5 to about 6.5.

In a twelfth aspect, the invention provides an aqueous solution of thesalt of formula (2) of the eleventh aspect that is a single-phase.

In a thirteenth aspect, the invention provides a method of making a saltof formula (2) comprising contacting a compound of formula (1) withcarbon dioxide, CS₂ or COS in the presence of water, thereby convertingthe compound to a salt form of formula (2).

In certain embodiments of the thirteenth aspect, the compound of formula(1) and the water are present in at least equimolar amounts. The {numberof moles of water} divided by the {number of moles of the compound offormula (1)} may be about 1 should it be desired to consume both thecompound of formula (1) and the water without leaving any unreactedamidine or water. In certain embodiments of the thirteenth aspect, thesalt of formula (2) precipitates.

In a fourteenth aspect, the invention provides a method of making anaqueous solution of a salt of formula (2) comprising contacting acompound of formula (1) with carbon dioxide, CS₂ or COS in the presenceof water thereby converting the compound to a salt of formula (2) thatis water soluble, wherein sufficient water is provided to solubilize theionic form of formula (2); and obtaining an aqueous solution of theionic form of formula (2).

In certain embodiments of the fourteenth aspect, the compound of formula(1) and the water are present in at least equal volumes. The {volume ofwater} divided by the {volume of the compound of formula (1)} may beabout 1 should it be desired to ensure the dissolution of the ionic formof formula (2), should this be a solid at the temperature at which it isformed.

In certain embodiments of the thirteenth and fourteenth aspects, thecontacting a compound of formula (1) with carbon dioxide, CS₂ or COS inthe presence of water comprises: preparing a two-phase liquid mixturecomprising water and a compound of formula (1); and contacting thetwo-phase liquid mixture with carbon dioxide, CS₂ or COS.

In certain embodiments of the thirteenth and fourteenth aspects, thecontacting a compound of formula (1) with carbon dioxide, CS₂ or COS inthe presence of water comprises: preparing an aqueous solution of carbondioxide, CS₂ or COS in water; and mixing the aqueous solution with acompound of formula (1).

In certain embodiments of the thirteenth and fourteenth aspects, thecontacting a compound of formula (1) with carbon dioxide, CS₂ or COS inthe presence of water comprises: dissolving carbon dioxide, CS₂ or COSin a compound of formula (1) to provide a non-aqueous liquid; and mixingthe non-aqueous liquid with water.

In a fifteenth aspect, the invention provides liquid comprising acompound of formula (1) of the tenth aspect, wherein when an appropriatetrigger is applied, the compound in aqueous mixture reversibly switchesbetween two states, a neutral water-immiscible state and an ionic state,that are distinguishable from one another by their polarities; andwherein a first said trigger, for converting the neutral state to theionic state in an aqueous mixture, is addition of CO₂ to the aqueousmixture; a second said trigger, for converting the ionic state to theneutral state in an aqueous solution comprising the compound in itsionic state and dissolved CO₂, is depletion of CO₂ from the aqueoussolution.

In a sixteenth aspect, the invention provides a liquid comprising acompound of formula (1), wherein when an appropriate trigger is applied,the compound in aqueous mixture reversibly switches between two states,a neutral state and a salt state, that are distinguishable from oneanother by their miscibilities with water; and wherein a first saidtrigger, for converting the neutral state to the ionic state in anaqueous mixture, is addition of CO₂ to the aqueous mixture, and a secondsaid trigger, for converting the ionic state to the neutral state in anaqueous solution comprising the compound in its ionic state anddissolved CO₂, is depletion of CO₂ from the aqueous solution.

In a seventeenth aspect, the invention provides a liquid comprising acompound of formula (1), wherein when an appropriate trigger is applied,the compound in aqueous mixture reversibly switches between two states,a neutral aqueous-immiscible state at a first partial pressure of CO₂and a salt aqueous-miscible state at a second partial pressure of CO₂that is higher than the first partial pressure of CO₂; and wherein afirst said trigger, for converting the neutral state to the ionic statein an aqueous mixture, is addition of CO₂ to the aqueous mixture, and asecond said trigger, for converting the ionic state to the neutral statein an aqueous solution comprising the compound in its ionic state anddissolved CO₂, is depletion of CO₂ from the aqueous solution.

In embodiments of the fifteenth, sixteenth and seventeenth aspects,depletion of CO₂ from the aqueous solution is obtained by: heating theaqueous mixture; placing the aqueous solution under reduced pressure;exposing the aqueous mixture to air; exposing the aqueous mixture to agas or gases that has insufficient CO₂ content to convert the neutralstate to the ionic state; flushing the aqueous mixture with a gas orgases that has insufficient CO₂ content to convert the neutral state tothe ionic state; or a combination thereof.

In an eighteenth aspect, the invention provides a method for separatinga selected substance from a mixture, comprising: adding a compound offormula (1) or formula (10) set forth below that is in a liquid state toa mixture of starting material(s) comprising a selected substance thatis water-immiscible; allowing the compound to solubilize the selectedsubstance; optionally isolating waste solid(s) from the mixture;contacting the mixture with water and carbon dioxide thereby convertingthe compound to a salt; allowing the mixture to separate into twodistinct phases; separating the two distinct phases to provide anisolated aqueous phase comprising an aqueous solution of the salt and anisolated non-aqueous phase comprising the selected substance; andwherein the selected substance is not reactive with the compound, carbondioxide, or a combination thereof.

The salt is a compound of formula (2) or formula (20). In certainembodiments of this aspect, the selected substance is a hydrophobiccompound. The desired substance may be a solid or a liquid, as long asit is soluble or miscible in the hydrophobic liquid.

In a nineteenth aspect, the invention provides a method for separating aselected liquid from a liquid mixture, comprising: forming a two-phasesystem by adding a compound of formula (1) or formula (10) set forthbelow to a liquid mixture comprising a selected liquid that iswater-immiscible and at least one further liquid that is immiscible withthe compound of formula (1) or formula (10); allowing the liquids tosettle into two different phases, a first phase comprising the selectedliquid and the compound of formula (1) or formula (10), and a secondphase comprising the at least one further liquid that is immiscible withthe compound of formula (1) or formula (10); separating the two phases;contacting the first phase with water and carbon dioxide, therebyconverting the compound of formula (1) or formula (10) to a salt;allowing the first phase to settle into two distinct phases, onecomprising the selected liquid and the other comprising an aqueoussolution of the salt; separating the two distinct phases to provide anisolated aqueous phase comprising an aqueous solution of the salt and anisolated non-aqueous phase comprising the selected liquid; and whereinthe selected liquid is not reactive with the compound, carbon dioxide ora combination thereof.

The salt is a compound of formula (2) or formula (20) set forth below.In certain embodiments of this aspect, the at least one further liquidthat is immiscible with the compound of formula (1) or formula (10) maybe water or a non-aqueous liquid. If the at least one further liquid isnon-aqueous, it is preferred that this has a higher polarity than thecompound of formula (1) or formula (10).

In certain embodiments of the eighteenth and nineteenth aspects, themethods further comprise: removing carbon dioxide from the isolatedaqueous phase to reform the compound of formula (1) or formula (10); andisolating the compound. The method of removing carbon dioxide from theisolated aqueous phase may comprise: heating the isolated aqueous phase,contacting the isolated aqueous phase with a nonreactive gas thatcontains substantially no carbon dioxide; or both heating and contactingwith a nonreactive gas that contains substantially no carbon dioxide.

In a twentieth aspect, the invention provides a method for converting asalt to a water-immiscible liquid comprising: preparing an aqueoussolution of a salt of formula (2) or formula (20) in which E is O;removing carbon dioxide from the aqueous solution to form a mixturecomprising water and a compound of formula (1) or formula (10); allowingthe mixture to separate into two distinct phases; and isolating anaqueous phase and a non-aqueous phase comprising the compound of formula(1) or formula (10).

In certain embodiments of the twentieth aspect, the method of removingcarbon dioxide comprises: heating the liquid, placing the isolatedaqueous phase under reduced pressure, contacting the liquid with anonreactive gas that contains substantially no carbon dioxide; or bothheating and contacting the liquid with a nonreactive gas that containssubstantially no carbon dioxide.

In certain embodiments of the eighteenth, nineteenth and twentiethaspects, the carbon dioxide is removed by contacting with a gas thatcontains substantially no CO₂, CS₂, or COS.

In another aspect the invention provides a compound of formula (10)

that is water-immiscible; where R⁵, R⁶, and R⁷ areindependently H; asubstituted or unsubstituted C₁ to C₁₀ alkyl group that is linear,branched, or cyclic; a substituted or unsubstituted C_(n)Si_(m) groupwhere n and m are independently a number from 0 to 10 and n+m is anumber from 1 to 10; a substituted or unsubstituted C₅ to C₁₀ arylgroup; a substituted or unsubstituted heteroaryl group having 4 to 10ring atoms; wherein, optionally, any combination of R⁵, R⁶ and R⁷, takentogether with the atoms to which they are attached join to form a ring;wherein a substituent is independently alkyl, alkenyl, alkynyl, aryl,aryl halide, heteroaryl, non-aromatic ring, Si(alkyl)₃, Si(alkoxy)₃,halo, alkoxy, amino, ester, amide, amidine, thioether, alkylcarbonate,phosphine, thioester, or a combination thereof.

In an embodiment of this aspect, the total number of carbon and/orsilicon atoms in all of R⁵, R⁶, and R⁷ is in the range of 5 to 12. In anembodiment of this aspect, the compound that has a logP value in therange of about 1.3 to about 3. In other embodiments of this aspect, thelogP value is in the range of about 1.5 to about 2.5.

In another aspect, the invention provides a salt of formula (20)

where R⁵, R⁶, and R⁷ are as defined for the compound of formula (10), nis a number from 1 to 6, sufficient to balance the charge of theammonium cation, and E is O, S or a combination of O and S, wherein thesalt is water-soluble and is prepared by a method comprising contactinga compound of formula (10) with at least one of CO₂, CS₂ or COS in thepresence of water, thereby converting the compound to the salt shown asformula (20).

In an embodiment of this aspect, E is oxygen and the salt is prepared bya method comprising contacting a compound of formula (10) with CO₂ inthe presence of water, thereby converting the compound to the salt shownas formula (20) in which E is oxygen. In certain embodiments of thisaspect, the total number of carbon and/or silicon atoms in all of R⁵,R⁶, and R⁷ is in the range of 5 to 12.

In an embodiment of this aspect, the compound has a logP value in therange of about 1.3 to about 3. In other embodiments, the logP value isin the range of about 1.5 to about 2.5.

In another aspect, the invention provides an aqueous solution of thesalt of the previous aspect that is single phase.

In yet another aspect, the invention provides a method of making a saltof formula (20) comprising contacting a compound of formula (10) with atleast one of CO₂, CS₂ or COS in the presence of water, therebyconverting the compound to a salt of formula (20).

In an embodiment of this aspect, the ratio of number of moles of waterto number of moles of the compound of formula (10) is about 1.

In another aspect, the invention provides a method of making an aqueoussolution of a salt of formula (20) comprising contacting a compound offormula (10) with at least one of CO₂, CS₂ or COS in the presence ofwater thereby converting the compound to a salt of formula (20) that iswater soluble, wherein sufficient water is provided to solubilize thesalt produced.

In an embodiment of this aspect, the ratio of volume of water to volumeof the compound of formula (10) is ≧ about 1. In an embodiment of thisaspect, the step of contacting a compound of formula (10) with at leastone of CO₂, CS₂ or COS in the presence of water comprises preparing atwo-phase mixture comprising water and a compound of formula (10); andcontacting the two-phase mixture with at least one of CO₂, CS₂ or COS.In other embodiments of this aspect, the step of contacting a compoundof formula (10) with at least one of CO₂, CS₂ or COS in the presence ofwater comprises preparing a solution of at least one of CO₂, CS₂ or COSin water; and mixing the solution with a compound of formula (10). Incertain embodiments of this aspect, the step of contacting a compound offormula (10) with at least one of CO₂, CS₂ or COS in the presence ofwater comprises dissolving at least one of CO₂, CS₂ or COS in a compoundof formula (10) to provide a non-aqueous liquid; and mixing thenon-aqueous liquid with water.

In another aspect, the invention provides a method for separating aselected substance from a mixture, comprising adding the compound offormula (10) that is in a liquid state to a mixture comprising aselected substance that is water-immiscible; allowing the compound tosolubilize the selected substance; optionally isolating waste solid(s)from the mixture; contacting the mixture with water and CO₂ therebyconverting the compound to a salt; allowing the mixture to separate intotwo distinct phases; and separating the two distinct phases to providean isolated aqueous phase comprising the salt and an isolatednon-aqueous phase comprising the selected substance; wherein theselected substance is not reactive with the compound, CO₂, or acombination thereof.

An embodiment of this aspect, further comprises removing CO₂ from theisolated aqueous phase to reform the water-immiscible compound offormula (10); and isolating the compound.

In an embodiment of this aspect removing CO₂ comprises heating theisolated aqueous phase; contacting the isolated aqueous phase with anonreactive gas that contains substantially no CO₂; or both heating andcontacting the isolated aqueous phase with a nonreactive gas thatcontains substantially no CO₂.

In another aspect, the invention provides a method for separating aselected liquid from a liquid mixture, comprising forming a two-phasesystem by adding a compound of formula (10) to a liquid mixturecomprising a selected liquid that is water-immiscible and at least onefurther liquid that is immiscible with the compound of formula (10),wherein a first phase comprises the selected liquid and the compound,and a second phase comprises the at least one further liquid that isimmiscible with the compound of formula (10); separating the two phases;contacting the first phase with water and CO₂, thereby converting thecompound to a salt and forming two distinct phases, one comprising theselected liquid and the other comprising an aqueous solution of thesalt; and separating the two distinct phases to provide an isolatedaqueous phase comprising the salt and an isolated non-aqueous phasecomprising the selected liquid; wherein the selected liquid is notreactive with the compound, CO₂ or a combination thereof.

An embodiment of this aspect further comprises removing CO₂ from theisolated aqueous phase to reform the compound; and isolating thecompound. In certain embodiments, removing CO₂ comprises heating theisolated aqueous phase, contacting the isolated aqueous phase with anonreactive gas that contains substantially no CO₂; or

-   both heating and contacting with a nonreactive gas that contains    substantially no CO₂.

In another aspect, the invention provides a method for converting a saltto a water-immiscible liquid comprising preparing an aqueous solution ofa salt of formula (20), removing CO₂ from the aqueous solution to form amixture comprising water and a compound of formula (10); allowing themixture to separate into two distinct phases; and isolating an aqueousphase and a non-aqueous phase comprising the compound of formula (10).In an embodiment of this aspect, removing CO₂ comprises

-   heating the liquid, contacting the liquid with a nonreactive gas    that contains substantially no CO₂; or both heating and contacting    the liquid with a nonreactive gas that contains substantially no    CO₂. In other embodiments, CO₂ is removed by contacting with a gas    that contains substantially no CO₂, CS₂, or COS. In some embodiments    of this aspect,-   the salt of formula (20) precipitates.

In another aspect, the invention provides a method of extracting ahydrophobic material from a solid that is at least partially coated bythe hydrophobic material, comprising combining a solid that is at leastpartially coated by a hydrophobic material and a solvent comprising acompound of formula (1) or a compound of formula (10) to form a mixtureof the solid in a homogeneous single-phase liquid, said liquidcomprising the compound and the hydrophobic material; separating thesolid from the single-phase liquid; combining in any order thesingle-phase liquid, water, and CO₂ to form a two-phase liquid mixturewherein a first phase is hydrophobic and comprises the hydrophobicmaterial and a second phase is aqueous and comprises water and awater-soluble or water-miscible bicarbonate salt of formula (2) or offormula (20).

In an embodiment of this aspect, the hydrophobic material is soluble ormiscible in the compound of formula (1) or in the compound of formula(10), but is not soluble nor miscible in a compound of formula (2) or acompound of formula (20).

In certain embodiments of this aspect the hydrophobic material is oil(e.g., motor oil) and the solid is plastic (e.g., polyethylene). In someembodiments, the plastic was previously used to contain the oil.

In another aspect, the invention provides a method of increasing densityof polymeric foam, comprising dissolving a polymeric foam in a liquidcomprising a compound of formula (1) or a compound of formula (10) toform a solution;

-   combining in any order the solution, water, and CO₂ to form a    suspension comprising solid polymer and an aqueous liquid comprising    bicarbonate salt of formula (2) or bicarbonate salt of formula (20);    and separating the suspension to obtain the solid polymer, wherein    the solid polymer has increased density relative to the polymeric    foam.

In an embodiment of this aspect, the polymeric foam is expandedpolystyrene, extruded polystyrene foam, or polystyrene foam packingchips.

In another aspect, the invention provides a method for separating aselected water-immiscible compound from a mixture, comprising adding aliquid comprising a compound of formula (1) or a compound of formula(10) to a first mixture, said first mixture comprising a selectedwater-immiscible compound that is soluble in the liquid, to form asecond mixture; combining in any order the second mixture, water, andCO₂ to form a two-phase liquid mixture having a first hydrophobic phasecomprising the selected water-immiscible compound and a second aqueousphase comprising bicarbonate salt of formula (2) or bicarbonate salt offormula (20); separating the two phases; wherein the selectedwater-immiscible compound is not reactive with the liquid, carbondioxide or a combination thereof.

In an embodiment of this aspect, the selected water-immiscible compoundis soluble or miscible in a compound of formula (1) or a compound offormula (10), but is not soluble nor miscible in a compound of formula(2) or a compound of formula (20).

Some embodiments of this aspect, further comprise separating from thesecond mixture one or more components of the first mixture that isinsoluble in the liquid.

In certain embodiments of this aspect, the first mixture isoil-contaminated soil. In other embodiments, the first mixture is amixture of two or more solids wherein a first solid is soluble in theliquid and a second solid is not. In some embodiments, the first mixtureis paper bearing ink wherein the ink is soluble in the liquid.

In another aspect, the invention provides a kit comprising a compound offormula (1) or a compound of formula (10), and optionally instructionsfor use. In an embodiment of this aspect, the kit is for deinking paper.In another embodiment of this aspect, the kit is for remediating soil.In yet another embodiment, the kit is for increasing the density of apolymeric foam. In another embodiment, the kit is for cleaningpolyethylene. In another embodiment, the kit is for use whensynthesizing biodiesel. In another embodiment, the kit is for separatinga selected substance from a mixture. In another embodiment, the kit isfor separating a selected liquid from a liquid mixture. In anotherembodiment, the kit is for separating a selected liquid from a mixtureof two or more solids. In yet another embodiment, the kit is forextracting a hydrophobic material from a solid. In some embodiments, thehydrophobic material is a coating on at least a portion of the solid.

In embodiments of the numerous above aspects, the compound of formula(10) is N-ethylpiperidine, N,N,N-triethylamine,N,N-diethyl-N-methylamine, N,N-dimethyl-N-cyclohexylamine,N,N-dimethyl-N-hexylamine, N,N-diethyl-N-butylamine,N,N-dipropyl-N-methylamine, N,N-diethyl-N-cyclohexylamine, orN-butylpyrrolidine.

In another aspect, the invention provides, a method of extracting ahydrophobic material from a solid that is at least partially coated bythe hydrophobic material, comprising: combining a solid that is at leastpartially coated by a hydrophobic material and a solvent comprising acompound of formula (1) or a compound of formula (10) to form a mixtureof the solid in a homogeneous single-phase liquid, said liquidcomprising the compound and the hydrophobic material; separating thesolid from the single-phase liquid; combining in any order thesingle-phase liquid, water, and CO₂ to form a two-phase liquid mixturewherein a first phase is hydrophobic and comprises the hydrophobicmaterial and a second phase is aqueous and comprises water and awater-soluble or water-miscible bicarbonate salt of formula (2) or offormula (20).

In some embodiments of this aspect, the hydrophobic material is solubleor miscible in a compound of formula (1) or in a compound of formula(10), but is not soluble nor miscible in a compound for formula (2) orin a compound of formula (20). In some embodiments of this aspect, thehydrophobic material is oil (e.g., motor oil) and the solid is plastic(e.g., polyethylene). The plastic may previously have been used tocontain the oil.

In another aspect, the invention provides a method of removing gas frompolymeric foam, comprising: dissolving a polymeric foam in a switchablehydrophilicity solvent to form a solution; combining in any order thesolution, water, and CO₂ to form a suspension comprising solid polymerand an aqueous liquid comprising a protonated switchable hydrophilicitysolvent; and separating the suspension to obtain the solid polymer.

In some embodiments of this aspect, the switchable hydrophilicitysolvent is a compound of formula (1) or (10). In some embodiments ofthis aspect, the polymeric foam is expanded polystyrene, extrudedpolystyrene foam, rigid polystyrene containers, high impact thinpolystyrene or polystyrene foam packing chips.

In another aspect, the invention provides method of obtainingsubstantially pure polymer from polymeric foam, comprising: dissolving apolymeric foam in a switchable hydrophilicity solvent to form asolution; combining in any order the solution, water, and CO₂ to form asuspension comprising solid polymer and an aqueous liquid comprising aprotonated form of the SHS; and separating the suspension to obtain thesolid polymer.

In another aspect, the invention provides a method of reducing air orgas content of a polymeric material or a mixture of polymeric materials,comprising: dissolving a polymeric material in a liquid comprising acompound of formula (1) or a compound of formula (10) to form asolution; combining in any order the solution, water, and CO₂ to form asuspension comprising solid polymer and an aqueous liquid comprisingbicarbonate salt of formula (2) or bicarbonate salt of formula (20); andseparating the suspension to obtain the solid polymer. In someembodiments of this aspect, the polymeric product comprises a mixture ofpolymers.

In another aspect, the invention provides a method for separating aselected water-immiscible compound from a mixture, comprising: adding aliquid comprising a compound of formula (1) or a compound of formula(10) to a first mixture, said first mixture comprising a selectedwater-immiscible compound that is soluble in the liquid, to form asecond mixture; combining in any order the second mixture, water, andCO₂ to form a two-phase liquid mixture having a first hydrophobic phasecomprising the selected water-immiscible compound and a second aqueousphase comprising bicarbonate salt of formula (2) or bicarbonate salt offormula (20); separating the two phases; wherein the selectedwater-immiscible compound is not reactive with the liquid, carbondioxide or a combination thereof.

In some embodiments of this aspect, the selected water-immisciblecompound is soluble or miscible in a compound of formula (1) or acompound of formula (10), but is not soluble nor miscible in a compoundof formula (2) or a compound of formula (20). In some embodiments ofthis aspect, the method further comprises separating from the secondmixture one or more components of the first mixture that is insoluble inthe liquid. In some embodiments of this aspect, the the first mixtureis: oil-contaminated soil; oil-sands, drilling fines, a mixture of twoor more solids wherein a first solid is soluble in the liquid and asecond solid is not; or paper bearing ink wherein the ink is soluble inthe liquid.

In some embodiments of numerous above aspects, the methods employ one ormore compounds of formula (10) selected from N-ethylpiperidine,N,N,N-triethylamine, N,N-diethyl-N-methylamine,N,N-dimethyl-N-cyclohexylamine, N,N-diethyl-N-cyclohexylamine,N,N-dimethyl-N-hexylamine, N,N-diethyl-N-butylamine,N,N-dipropyl-N-methylamine, N-butylpyrrolidine,N,N′-dipropyl-N,N′-diethylbutane-1,4-diamine,N1,N1,N4,N4-tetraethylbutane-1,4-diamine, or any combination thereof.

In another aspect, the invention provides use of a switchablehydrophilicity solvent, wherein when an appropriate trigger is applied,the compound reversibly switches between two states, a neutralwater-immiscible state and an ionic water-miscible state; and wherein afirst said trigger, for converting the neutral state to the ionic state,is addition of CO₂ to an aqueous mixture; and a second said trigger, forconverting the ionic state to the neutral state in an aqueous mixturecomprising dissolved CO₂, is depletion of CO₂ from the aqueous mixture.

In some embodiments of this aspect, the switchable hydrophilicitysolvent comprises a compound of formula (10). In some embodiments ofthis aspect, depletion of CO₂ from the aqueous mixture is obtained by:heating the aqueous mixture; placing the aqueous mixture under reducedpressure, exposing the aqueous mixture to air; exposing the aqueousmixture to a gas or gases that has insufficient CO₂ content to convertthe neutral state to the ionic state; flushing the aqueous mixture witha gas or gases that has insufficient CO₂ content to convert the neutralstate to the ionic state; or a combination thereof.

In another aspect, the invention provides use of a switchablehydrophilicity solvent comprising a compound of formula (10),

that is water-immiscible; where R⁵, R⁶, and R⁷ areindependently H; asubstituted or unsubstituted C₁ to C₁₀ alkyl group that is linear,branched, or cyclic; a substituted or unsubstituted C_(n)Si_(m) groupwhere n and m are independently a number from 0 to 10 and n+m is anumber from 1 to 10; a substituted or unsubstituted C₅ to C₁₀ arylgroup; a substituted or unsubstituted heteroaryl group having 4 to 10ring atoms; wherein, optionally, any two of R⁵, R⁶ and R⁷, takentogether with the atoms to which they are attached join to form a ring;wherein a substituent is independently alkyl, alkenyl, alkynyl, aryl,aryl halide, heteroaryl, non-aromatic ring, Si(alkyl)₃, Si(alkoxy)₃,halo, alkoxy, amino, ester, amide, amidine, thioether, alkylcarbonate,phosphine, thioester, or a combination thereof.

In some embodiments of this aspect, the total number of carbon and/orsilicon atoms in all of R⁵, R⁶, and R⁷ is in the range of 5 to 12. Insome embodiments of this aspect, the compound of formula (10) has a logPvalue in the range of about 1.3 to about 3. In some embodiments of thisaspect, the compound of formula (10) has a logP value is in the range ofabout 1.5 to about 2.5.

In another aspect, the invention provides use of a switchablehydrophilicity solvent whose salt form is a compound of formula (20)

where R⁵, R⁶, and R⁷ are as defined in claim 113, n is a number from 1to 6 sufficient to balance charge of the ammonium cation, and E is O, Sor a combination of O and S, wherein the salt is water-soluble and isprepared by a method comprising: contacting a compound of claim 113 withat least one of CO₂, CS₂ or COS in the presence of water, therebyconverting the compound to the salt shown as formula (20).

In some embodiments of this aspect, E is oxygen and the salt is preparedby a method comprising: contacting a compound of claim 113 with CO₂ inthe presence of water, thereby converting the compound to the salt shownas formula (20) in which E is oxygen. In some embodiments of thisaspect, the total number of carbon and/or silicon atoms in all of R⁵,R⁶, and R⁷ is in the range of 5 to 12. In some embodiments of thisaspect, the compound of formula (10) has a logP value in the range ofabout 1.3 to about 3. In some embodiments of this aspect, the logP valueis in the range of about 1.5 to about 2.5.

In another aspect, the invention provides use of a switchablehydrophilicity solvent for selective extraction and collection of aselected hydrophobic compound. In some embodiments of this aspect, theswitchable hydrophilicity solvent is a compound of formula (1) or acompound of formula (10). In some embodiments of this aspect, the SHScomprises N-ethylpiperidine, N,N,N-triethylamine,N,N-diethyl-N-methylamine, N,N-dimethyl-N-cyclohexylamine,N,N-diethyl-N-cyclohexylamine, N,N-dimethyl-N-hexylamine,N,N-diethyl-N-butylamine, N,N-dipropyl-N-methylamine,N-butylpyrrolidine, N,N′-dipropyl-N,N′-diethylbutane-1,4-diamine,N1,N1,N4,N4-tetraethylbutane-1,4-diamine, or any combination thereof.

In another aspect, the invention provides a kit comprising a switchablehydrophilicity solvent, and optionally instructions for use. In someembodiments of this aspect, the kit includes SHS as a solid bicarbonatesalt and the instructions indicate how to switch the salt to its neutralhydrophobic form.

BRIEF DESCRIPTION OF THE DRAWINGS

For a better understanding of the invention and to show more clearly howit may be carried into effect, reference will now be made by way ofexample to the accompanying drawings, which illustrate aspects andfeatures according to embodiments of the present invention, and inwhich:

FIG. 1 shows a chemical reaction equation and a schematic of theswitching reaction between hydrophobic and hydrophilic forms of anamidine.

FIG. 2 presents the hydrophilicity/ hydrophobicity of various liquids byindicating calculated logP values for each liquid.

FIG. 3A presents a comparison of the polarity ofN,N,N′-tributylpentanamidine, shown as an open square, and an aqueoussolution of N,N,N′-tributylpentanamidinium bicarbonate, shown as a blacksquare, as measured by the change in the maximum wavelength ofabsorption in nm of the solvatochromatic dye Nile Red, with othersolvents and switchable systems. The conventional solvents listed alongthe horizontal wavelength axis are diethyl ether (ether), toluene,acetone, acetonitrile (MeCN), chloroform (CHCl₃), dimethyl formamide(DMF), methanol (MeOH) and ethylene glycol. The change in maximumwavelength of absorption of BA/water is compared to1,8-diazabicyclo[5.4.0]undec-7-ene/propanol (DBU/PrOH);1,1,3,3-tetramethyl-2-butylguanidine/methanol (TMBG/MeOH);N,N-methylbenzylamine (NHMeBn); and N,N-ethylbenzylamine (NHEtBn).

FIG. 3B presents the method of separating a selected liquid from amixture comprising the selected liquid (“oil”), as disclosed herein. Inthis embodiment the selected liquid is soy oil and the mixturecomprising the selected liquid includes soy flakes.

FIG. 4A shows a ¹H NMR spectrum of N,N,N′-tripropylbutyramidine in CDCl₃at 400 MHz. FIG. 4B shows a ¹H NMR spectrum ofN,N,N′-tripropylbutyramidinium bicarbonate in D₂O at 400 MHz.

FIG. 5A shows a ¹³C NMR spectrum of N,N,N′-tripropylbutyramidine inCDCl₃ at 100 MHz. FIG. 5B shows a ¹³C NMR spectrum ofN,N,N′-tripropylbutyramidinium bicarbonate in D₂O at 100 MHz.

FIG. 6A shows an IR spectrum of N,N,N′-tripropylbutyramidine betweenpotassium bromide plates. FIG. 6B shows an IR spectrum ofN,N,N′-tripropylbutyramidinium chloride between potassium bromideplates.

FIG. 7A shows a ¹H NMR spectrum of N,N,N′-tributylpentanamidine in CDCl₃at 400 MHz. FIG. 7B shows a ¹H NMR spectrum ofN,N,N′-tributylpentanamidinium bicarbonate in D₂O at 400 MHz.

FIG. 8A shows a ¹³C NMR spectrum of N,N,N′-tributylpentanamidine inCDCl₃ at 100 MHz. FIG. 8B shows a ¹³C NMR spectrum ofN,N,N′-tributylpentanamidinium bicarbonate in D₂O at 100 MHz.

FIG. 9A shows an IR spectrum of N,N,N′-tributylpentanamidine betweenpotassium bromide plates. FIG. 9B shows an IR spectrum ofN,N,N′-tributylpentanamidinium chloride between potassium bromideplates.

FIG. 10 shows multiple ¹H NMR spectra from aN,N,N′-tributylpentanamidine/N,N,N′-tributylpentanamidiniumbicarbonate/D₂O switchability study carried out in methanol-d₄ at 400MHz with a sodium acetate internal standard. This is discussed inExample 1D below.

FIG. 11 shows multiple ¹H NMR spectra in CDCl₃ of an extraction studyusing N,N,N′-tributylpentanamidine with soybean oil (top), soybean oiland N,N,N′-tributylpentanamidine (middle) and soybean oil afterswitching (bottom). The spectra are discussed in Example 2 below.

FIG. 12 shows a chemical reaction equation and a schematic of theswitching reaction between hydrophobic and hydrophilic forms of anamine.

FIG. 13 shows structural formulae and calculated logP values for threegroups of various amines. Those in the left group are miscible withwater under air or nitrogen and are therefore not switchablehydrophilicity solvents under experimental conditions described herein.Those on the right are immiscible with water even after CO₂ gas isbubbled through the liquid mixture and are therefore not switchablehydrophilicity solvents under experimental conditions described herein.Those in the middle section of the figure are immiscible with waterunder air or nitrogen but become miscible with water after CO₂ isbubbled through the liquid mixture and are therefore switchablehydrophilicity solvents under experimental conditions described herein.

FIG. 14 graphically shows change in mass of soybean flakes vs. timeduring soybean oil extraction using N,N-dimethylcyclohexylamine at 25°C. and 60° C., contrasted to extraction using hexanes at 60° C., asdescribed in Example 2B.

FIG. 15 is a schematic depiction of a system of the invention emplying aswitchable hydrophilicity solvent (SHS).

FIG. 16 is a schematic depiction of a system of the invention forremoving particles of contaminated solid.

FIG. 17 is a schematic depiction of a system of the invention forextraction of a selected material from a solid.

FIG. 18 is a schematic depiction of a system of the invention forisolation of a component in a chemical synthesis.

FIG. 19 is a schematic depiction of a system of the invention forisolation of a plastic from a mixture of plastics.

FIG. 20 is a schematic depiction of a system of the invention for addinga hydrophobic compound or compounds to a material.

DETAILED DESCRIPTION OF THE INVENTION

Use of conventional solvent provides a volatile liquid with which tosolubilise hydrophobic compounds; however, drawbacks of suchconventional solvents include their single polarity, toxicity, and thattheir removal requires costly and energy intensive distillation and itsassociated environmental impact. The invention described herein includessystems that provide a distillation-free alternative to conventionalsolvents. Such systems use solvents that can be reversibly convertedbetween two states. In a first state, the system uses an unprotonatedneutral compound that is a liquid that is not miscible with water, butrather is hydrophobic and can act as a solvent to dissolve hydrophobiccompounds. In a second state, the system uses a protonated form of thecompound of the first state, which protonated compound is hydrophilicand is miscible with water. Such systems provide controlledswitchability between the two states such that they can be generatedover and over again.

That is, solvents that reversibly convert from a hydrophobicwater-immiscible form to a hydrophilic water-miscible form upon contactwith water and a trigger such as contact with CO₂, are described. Thehydrophilic form is readily converted back to the hydrophobic form andwater. Such solvents are referred to herein as switchable hydrophilicitysolvents. The following terms are used in this description.

Definitions

As used herein, “switchable hydrophilicity solvent” refers to a compoundthat, in the presence of water or other aqueous solution, exists in anaqueous-immiscible state at a first partial pressure of CO₂ and existsin an aqueous-miscible state at a second partial pressure of CO₂ that ishigher than the first partial pressure of CO₂. That is, this term refersto a solvent that, in the presence of water or other aqueous solution,can be changed from an aqueous-immiscible liquid state to anaqueous-miscible state by raising the partial pressure of CO₂, and thatcan be changed from an aqueous-miscible state to an aqueous-immisciblestate by lowering the partial pressure of CO₂. This term also applies tothe case wherein COS, CS₂, or a mixture of any or all of CO₂, COS, orCS₂, is employed in place of the CO₂ recited above.

It should of course be understood that for the purposes of thisapplication the terms “water-immiscible” and “aqueous-immiscible” areused interchangeably and the terms “water-miscible” and“aqueous-miscible” are used interchangeably.

As used herein, “aliphatic” refers to hydrocarbon moieties that arelinear, branched or cyclic, may be alkyl, alkenyl or alkynyl, and may besubstituted or unsubstituted. “Aryl” means a moiety including asubstituted or unsubstituted aromatic ring, including heteroarylmoieties and moieties with more than one conjugated aromatic ring;optionally it may also include one or more non-aromatic ring. “C₅ to C₁₀Aryl” means a moiety including a substituted or unsubstituted aromaticring having from 5 to 10 carbon atoms in one or more conjugated aromaticrings. Examples of aryl moieties include phenyl, biphenyl, naphthyl andxylyl.

As used herein, “heteroaryl” means a moiety including a substituted orunsubstituted aromatic ring or ring system having from 3 to 20, or 4 to10 carbon atoms and at least one heteroatom in one or more conjugatedaromatic rings. As used herein, “heteroatom” refers to non-carbon andnon-hydrogen atoms, such as, for example, O, S, and N. Examples ofheteroaryl moieties include pyridyl, bipyridyl, indolyl, thienyl, andquinolinyl.

As used herein, “substituted” means having one or more substituentmoieties whose presence does not interfere with the desired reaction.Examples of substituents include alkyl, alkenyl, alkynyl, aryl,aryl-halide, heteroaryl, cyclyl (non-aromatic ring), Si(alkyl)₃,Si(alkoxy)₃, halo, alkoxyl, amino, amide, amidine, hydroxyl, thioether,alkylcarbonyl, alkylcarbonyloxy, arylcarbonyloxy, alkoxycarbonyloxy,aryloxycarbonyloxy, carbonate, alkoxycarbonyl, aminocarbonyl,alkylthiocarbonyl, phosphate, phosphate ester, phosphonato, phosphinato,cyano, acylamino, imino, sulfhydryl, alkylthio, arylthio,thiocarboxylate, dithiocarboxylate, sulfate, sulfato, sulfamoyl,sulfonamide, nitro, nitrile, azido, heterocyclyl, ether, ester,silicon-containing moieties, thioester, or a combination thereof.Preferable substituents are alkyl, aryl, heteroaryl, and ether. In someembodiments, substituents include an amine or an amidine moiety. It isnoted that aryl halides are acceptable substituents. Alkyl halides areknown to be quite reactive, and are acceptable so long as they do notinterfere with the desired reaction.

As used herein, “short chain aliphatic” or “lower aliphatic” refers toC₁ to C₄ aliphatic. “Long chain aliphatic” or “higher aliphatic” refersto C₅ to C₁₀ aliphatic.

As used herein, the term “unsubstituted” refers to any open valence ofan atom being occupied by hydrogen. Also, if an occupant of an openvalence position on an atom is not specified then it is hydrogen.

The term “switched” means that the physical properties and, inparticular, the hydrophilicity have been modified. “Switchable” meansable to be converted from a first state with a first set of physicalproperties, e.g., a hydrophobic state, to a second state with a secondset of physical properties, e.g., a hydrophilic state, or vice-versafrom the second state to the first state. A “trigger” is a change ofconditions (e.g., introduction or removal of a gas, change intemperature) that causes a change in the physical properties, e.g.hydrophilicity. The term “reversible” means that the reaction canproceed in either direction (backward or forward) depending on thereaction conditions.

As used herein, “carbonated water” means a solution of water in whichcarbon dioxide has been dissolved. “Carbon dioxide saturated water”means a solution of water in which carbon dioxide is dissolved to themaximum extent at that temperature and pressure.

As used herein, “a gas that has substantially no carbon dioxide” meansthat the gas has insufficient carbon dioxide content to interfere withthe removal of carbon dioxide from the solution. For some applications,air may be a gas that has substantially no carbon dioxide. Untreated airmay be successfully employed, i.e., air in which the carbon dioxidecontent is unaltered; this would provide a cost saving. For instance,air may be a gas that has substantially no carbon dioxide because insome circumstances, the approximately 0.04% by volume of carbon dioxidepresent in air is insufficient to maintain a compound in a switchedform, such that air can be a trigger used to remove carbon dioxide froma solution and cause switching. Similarly, “a gas that has substantiallyno carbon dioxide, CS₂ or COS” has insufficient carbon dioxide, CS₂ orCOS content to interfere with the removal of carbon dioxide, CS₂ or COSfrom the solution.

As used herein, “coating” or “coated” refers to placement of, forexample, a hydrophobic material, on or proximal to a solid's surface,but does not exclude impregnation of the solid where it is able toabsorb all or part of the hydrophobic material.

As used herein, the term “contaminant” refers to one or more compoundsthat is intended to be removed from a mixture and is not intended toimply that the contaminant has no value. For example, oil, which hassignificant value, may conveniently be called a contaminant whendescribing oil sands.

As used herein, the term “substantially pure” refers to having anapproximately homogeneous or uniform composition. A substantially puresample has a preponderance of one component and any impurity is presentonly in trace amounts.

As used herein, the term “migration” refers to movement of a substancefrom a first location to a second location. For illustrative purposes,in a non-limiting example, a substance may be present in a first layerof a two-layer system and then, due to a change in conditions, maymigrate to the second layer of the system.

As used herein, “amidine” (see compound of formula (1) below) refers toa molecule with a structure R¹N═C(R²)—NR³R⁴, where R¹ through R⁴ arehydrogen or aliphatic or aryl or heteroaryl as discussed below. Theionic form (salt) of an amidine (see compound of formula (2) below) istermed an “amidinium salt”. The bicarbonate salt of an amidine (seecompound of formula (3) below) is termed an “amidinium bicarbonate”. Itshould be noted that amidine as used herein also includes the structureR¹N═CH—NR³R⁴ (i.e., R² is replaced by H), where R¹, R³, and R⁴ are asdiscussed above.

As used herein, “amine” (see compound of formula (10) below) refers to amolecule with a structure NR⁵R⁶R⁷, where R⁵ through R⁷ are hydrogen oraliphatic or aryl or heteroaryl as discussed below. The ionic form(salt) of an amine (see compound of formula (20) below) is termed an“ammonium salt”. The bicarbonate salt of an amine (see compound offormula (30) below) is termed an “ammonium bicarbonate”.

As used herein, “in the presence of water” means that at least a smallamount of water is present. In many cases the ratio of switchablehydrophilicity solvent to water (by volume) for the formation of thehydrophilic protonated form of the solvent can be any ratio, e.g. 1:1,1:2, 1:3, 1,:4, etc. “Ionic” means containing or involving or occurringin the form of positively or negatively charged ions, i.e., chargedmoieties. “Neutral” as used herein means that there is no net charge.“Ionic salt”, “salt” and “ionic form” as used herein are usedinterchangeably to refer to compounds formed from positively andnegatively charged ions, these terms do not imply a physical state(i.e., liquid, gas or solid). For purposes of this disclosure, “ionicliquids” are salts that are liquid below 100° C.; such liquids aretypically nonvolatile, polar and viscous. “Nonionic liquids” meansliquids that do not consist primarily of molecules with formal chargessuch as ions. Nonionic liquids are available in a wide range ofpolarities and may be polar or nonpolar; they are typically morevolatile and less viscous than ionic liquids.

As used herein,a “polar” molecule is a molecule in which some separationoccurs of the centres of positive and negative charge. Polar solventsare typically characterized by a dipole moment. Ionic liquids areconsidered to be polar solvents, even though a dipole may not bepresent, because they behave in the same manner as polar liquids interms of their ability to solubilize polar solutes, their miscibilitywith other polar liquids, and their effect on solvatochromic dyes. Apolar solvent is generally better than a nonpolar (or less polar)solvent at dissolving polar or charged molecules.

As used herein, “Nonpolar” means having weak solvating power of polar orcharged molecules. Nonpolar solvents are associated with either havinglittle or no separation of charge, so that no positive or negative polesare formed, or having a small dipole moment. A nonpolar solvent isgenerally better than a polar solvent at dissolving nonpolar, waxy, oroily molecules. As used herein, “hydrophobicity” is a property of acompound or molecules of a compound leading it to be repelled from amass of water. Hydrophobic molecules are usually nonpolar have little orno hydrogen bonding ability. Such molecules are thus compatible withother neutral and nonpolar molecules. The degree of hydrophobiccharacter of the compound, or hydrophobicity, can be quantified by alogP value. The logP is the logarithm of the 1-octanol (lipid)-waterpartition coefficient, P, of a compound. This partition coefficientseeks to determine the ratio of solubilities of a molecule in a lipidenvironment and a hydrophilic aqueous environment. The lipid-waterpartition coefficient is the equilibrium constant calculated as theratio of the concentration of the compound in the lipid phase divided bythe concentration of the molecule in the aqueous phase, when those twophases are in contact with each other and when the compound has beenallowed enough time to reach its equilibrium concentrations in bothphases. P is sometimes referred to as K_(ow), and logP is sometimesreferred to as log K_(ow).

Partition coefficients can be experimentally determined using n-octanolas a model of the lipid phase and an aqueous phosphate buffer at pH 7.4as a model of the water phase. Because the partition coefficient is aratio, it is dimensionless. The partition coefficient is an additiveproperty of a molecule, because each functional group helps determinethe hydrophobic or hydrophilic character of the molecule. If the logPvalue is small, the molecule will be miscible with water such that thewater and molecule will form a single-phase in most proportions. If thelogP value is large, the compound will be immiscible with water suchthat a two-phase liquid mixture will be formed with the water andmolecule present as separate layers in most proportions.

It is also possible to theoretically calculate logP values because ofthe additive nature of the partition coefficient arising from theindividual functional groups of a molecule. A number of computerprograms are available for calculating logP values. The logP valuesdescribed herein are predicted using ALOGPS 2.1 software, whichcalculates the logP value for a given molecule using nine differentalgorithms and then averages the values. This computational method isfully described by Tetko I. V. and Tanchuk V. Y. in J. Chem. Inf.Comput. Sci., 2002, 42, 1136-1145 and in J. Comput. Aid. Mol. Des.,2005, 19, 453-463, both of which are incorporated herein by reference.

In contrast to hydrophobicity, “hydrophilicity” is a property of amolecule allowing it to transiently bond with water through hydrogenbonding. Hydrophilic molecules are usually polar. Such molecules maythus be compatible with other polar molecules.

As used herein, “insoluble” refers to a solid in a specified liquid thatis not well solubilized but rather forms a heterogeneous mixture. It isrecognized that the solubility of an “insoluble” solid in a specifiedliquid might not be zero but rather it would be smaller than that whichis useful in practice. The use of the terms “soluble”, “insoluble”,“solubility” and the like are not intended to imply that only asolid/liquid mixture is intended. For example, a statement that acompound is soluble in water is not meant to imply that the compoundmust be a solid; the possibility that the compound may be a liquid isnot excluded.

As used herein, “misciblility” is a property of two liquids that whenmixed provide a homogeneous solution. In contrast, “immiscibility” is aproperty of two liquids that when mixed provide a heterogeneous mixture,for instance having two distinct phases.

As used herein, “immiscible” means unable to merge into a single-phase.Thus two liquids are described as “immiscible” if they form two phaseswhen combined in a proportion. This is not meant to imply thatcombinations of the two liquids will be two-phase mixtures in allproportions or under all conditions. The immiscibility of two liquidscan be detected if two phases are present, for example via visualinspection. The two phases may be present as two layers of liquid, or asdroplets of one phase distributed in the other phase. The use of theterms “immiscible”, “miscible”, “miscibility” and the like are notintended to imply that only a liquid/liquid mixture is intended. Forexample, a statement that a compound is miscibile with water is notmeant to imply that the compound must be a liquid; the possibility thatthe compound may be a solid is not excluded.

“NMR” means Nuclear Magnetic Resonance. “IR spectroscopy” means infraredspectroscopy. “UV spectroscopy” means ultraviolet spectroscopy.

As used herein, “wet diethyl ether” means diethyl ether whose containerhas been opened to the atmosphere such that water from the airsurrounding the container has entered the solvent.

Embodiments

The invention provides systems that include switchable hydrophilicitysolvents. In an embodiment of the invention, the switchablehydrophilicity solvents is a compound of formula (1) below,

that is immiscible with water;

where R¹, R², R³, and R⁴ are independently H; a substituted orunsubstituted C₁ to C₁₀ alkyl group that is linear, branched, or cyclic;a substituted or unsubstituted C_(n)Si_(m) group where n and m areindependently a number from 0 to 10 and n +m is a number from 1 to 10; asubstituted or unsubstituted C₅ to C₁₀ aryl group; a substituted or asubstituted or unsubstituted heteroaryl group having 4 to 10 atoms inthe aromatic ring;

wherein a substituent is independently alkyl, alkenyl, alkynyl, aryl,aryl halide, heteroaryl, non-aromatic rings, Si(alkyl)₃, Si(alkoxy)₃,halo, alkoxy, amino, ester, amide, amidine, thioether, alkylcarbonate,phosphine, thioester, or a combination thereof.

Representative example of compounds of formula (1) include the followingcompounds:

The above two molecules have been synthesized, characterized and tested(see Example 4). They were both determined to be switchablehydrophilicity solvents since they were reversibly switched betweenwater-miscible and water-immiscible states as described herein. Notably,amidines that are water-immiscible are rare. Commercially availableamidines have been tested and were determined to be unsuitable asswitchable hydrophilicity solvents since they were water-miscible intheir neutral (unprotonated) forms. These compounds were:1,8-diazabicyclo-[5.4.0]-undec-7-ene (DBU) and Me₂N—C(═N-hexyl)Me.

A mixture of amidines may be used instead of a single amidine.

In another embodiment of the invention, the switchable hydrophilicitysolvents is a compound of formula (10) below,

that is immiscible with water;

where R⁵, R⁶, and Rare independently H; a substituted or unsubstitutedC₁ to C₁₀ alkyl group that is linear, branched, or cyclic; a substitutedor unsubstituted C_(n)Si_(m) group where n and m are independently anumber from 0 to 10 and n +m is a number from 1 to 10; a substituted orunsubstituted C₅ to C₁₀ aryl group; a substituted or a substituted orunsubstituted heteroaryl group having 4 to 10 atoms in the aromaticring;

wherein a substituent is independently alkyl, alkenyl, alkynyl, aryl,aryl halide, heteroaryl, non-aromatic rings, Si(alkyl)₃, Si(alkoxy)₃,halo, alkoxy, amino, ester, amide, amidine, thioether, alkylcarbonate,phosphine, thioester, or a combination thereof.

The amine can be primary, secondary or tertiary. In a preferredembodiment, the amine is tertiary.

A mixture of amines may be used instead of a single amine. In oneembodiment, the mixture of amines comprises a greater portion oftertiary amine(s) and a lesser portion of primary or secondary amine(s).Mixtures of compounds of formula (1), mixtures of compounds of formula(10), and mixtures of a compound of formula (1) and a compound offormula (10) are also suitable as switchable hydrophilicity solvents. Incertain embodiments, mixtures of two or more switchable hydrophilicitysolvents are used to modulate viscosity of the solvent. By matchingviscosities of the SHS and a liquid for extraction and isolation, it ispossible to minimize formation of emulsion.

In certain embodiments of formulas (1), any combination of R¹, R², R³and R⁴, taken together with the atoms to which they are attached, arejoined to form a cyclic ring. In some embodiments, they form aheterocyclic ring. In some embodiments, the ring has 4 to 8 ring atoms.

In certain embodiments of formulas (10), any combination of R⁵, R⁶, andR⁷, taken together with the nitrogen atom to which they are attached,are joined to form a heterocyclic ring. In some embodiments, the ringhas 4 to 8 ring atoms.

The compound of formula (1) described above is an amidine. The compoundof formula (10) described above is an amine. In the liquid state, acompound of formula (1) that is immiscible with water is hydrophobic innature and can function as a solvent for water-immiscible andwater-insoluble substances. In the liquid state, a compound of formula(10) that is immiscible with water is hydrophobic in nature and canfunction as a solvent for water-immiscible and water-insolublesubstances.

The water-immiscible compound of formula (1) or of formula (10) canadvantageously be converted from its hydrophobic form to a secondhydrophilic form when subjected, in the presence of water, with a gasthat liberates hydrogen ions. The second hydrophilic form is a salt thatforms a single-phase ionic solution with water. More particularly, theionic form is an amidinium salt or an ammonium salt. The aqueous ionicsolution can be switched back when an appropriate trigger is applied, toform (or re-form) a two-phase hydrophobic liquid and water mixture. Inthis situation the trigger causes deprotonation of the amidinium orammonium ion's nitrogen atom. Deprotonation is caused by expulsion fromthe solution of a gas that liberates hydrogen ions. Accordingly aspectsof the invention provide a solvent that can either mix with or separatefrom water in a controllable manner.

As used herein, gases that liberate hydrogen ions in an aqueousenvironment, (which are referred to herein as “gases that liberatehydrogen ions”) fall into two groups. Group (i) includes gases thatliberate hydrogen ions in the presence of a base, for example, HCN andHCl (water may be present, but is not required). Group (ii) includesgases that when dissolved in water react with water to liberate hydrogenions, for example, CO₂, NO₂, SO₂, SO₃, CS₂ and COS. For example, CO₂ inwater will produce HCO₃ ⁻ (bicarbonate ion) and CO₃ ²⁻ (carbonate ion)and hydrogen counterions, with bicarbonate being the predominant speciesat pH 7. One skilled in the art will recognize that the gases of group(ii) will liberate a smaller amount of hydrogen ions in water in theabsence of a base, and will liberate a larger amount of hydrogen ions inwater in the presence of a base.

Preferred gases that liberate hydrogen ions are those wherein the saltswitches to its hydrophobic liquid (amidine or amine) form when the samegas is expelled from the environment. CO₂ is particularly preferred.Hydrogen ions produced from dissolving CO₂ in water protonate theamidine (or amine). In such solution, the counterion for the amidiniumion (or ammonium ion) is predominantly bicarbonate. However, somecarbonate ions are also present in solution and the possibility that,for example, two amidinium molecules (or two ammonium molecules), eachwith a single positive charge, associate with a carbonate counterion isnot excluded. When CO₂ is expelled from the solution, the amidiniumcation (or ammonium cation) is deprotonated and thus is converted to itshydrophobic amidine (or amine) form.

Of group (ii) gases that liberate hydrogen ions, CS₂ and COS arereasonably expected to behave similarly to CO₂ such that they arereversibly switchable. However, they are not preferred because their usein conjunction with water and an amidine or amine could cause theformation of highly toxic H₂S. In some embodiments, CS₂ is not preferredfor the switching of certain amidines because of an undesired reactionin which CS₂ cleaves the amidine. This undesired cleavage does nothappen to amines and it does not happen to some amidines. In someembodiments of the invention, alternative gases that liberate hydrogenions are used instead of CO₂, or in combination with CO₂, or incombination with each other. Alternative gases that liberate hydrogenions (e.g., HCl, SO₂, HCN) are less preferred because of the added costsof supplying them and recapturing them, if recapturing is appropriate.However, in some applications one or more such alternative gases may bereadily available and therefore add little to no extra cost. Many suchgases, or the acids generated from their interaction with water, arelikely to be so acidic that the reverse reaction, i.e., converting theamidinium or ammonium salt to the amidine or amine hydrophobic liquid,may not proceed to completion as easily as the corresponding reactionwith CO₂. Group (i) gases HCN and HCl are less preferred triggersbecause of their toxicity and because reversibility would likely requirea strong base.

The present invention provides a salt of formula (2) where R¹, R², R³,and R⁴ are as defined for the compound of formula (1), n is a numberfrom 1 to 6 sufficient to balance the overall charge of the amidiniumcation, and E is O, S or a mixture of O and S,

that is water-soluble and that was prepared by a method comprising:

contacting a water-immiscible compound of formula (1) with carbondioxide, CS₂ or COS in the presence of water, thereby converting thecompound to the salt of formula (2).

The contacting of a water-immiscible compound of formula (1) with carbondioxide, CS₂ or COS in the presence of water may comprise:

preparing a two-phase liquid mixture comprising water and awater-immiscible compound of formula (1); and

contacting the two-phase liquid mixture with carbon dioxide, CS₂ or COS.

Alternatively, the contacting of a water-immiscible compound of formula(1) with carbon dioxide, CS₂ or COS in the presence of water maycomprise:

preparing an aqueous solution of carbon dioxide, CS₂ or COS in water;and mixing the aqueous solution with a water-immiscible compound offormula (1).

Alternatively, the contacting of a water-immiscible compound of formula(1) with carbon dioxide, CS₂ or COS in the presence of water maycomprise:

dissolving carbon dioxide, CS₂ or COS in a water-immiscible compound offormula (1) to provide a non-aqueous liquid; and

mixing the non-aqueous liquid with water.

The salt of formula (2) is water-soluble and can therefore form asingle-phase aqueous solution when dissolved in water. This is anextremely advantageous property which can be used to separate a compoundof formula (1) from a substance which is miscible with the compound offormula (1), but is water-immiscible, by converting the compound offormula (1) to a water-soluble salt of formula (2).

Furthermore, the water-soluble salt of formula (2) may be converted backinto a water-immiscible compound of formula (1) by removal of a gas thatliberates hydrogen ions from the solution. This is advantageous becauseit allows the re-use of the compound of formula (1) that iswater-immiscible.

The present invention provides a salt of formula (20) where R⁵, R⁶, andR⁷ are as defined for the compound of formula (10), n is a number from 1to 6 sufficient to balance the overall charge of the ammonium cation,and E is O, S or a mixture of O and S,

that is water-soluble and that was prepared by a method comprising:

contacting a water-immiscible compound of formula (10) with carbondioxide, CS₂ or COS in the presence of water, thereby converting thecompound to the salt of formula (20).

The contacting of a water-immiscible compound of formula (10) withcarbon dioxide, CS₂ or COS in the presence of water may comprise:

preparing a two-phase mixture comprising water and a water-immisciblecompound of formula (10); and

contacting the two-phase mixture with carbon dioxide, CS₂ or COS.

Alternatively, the contacting of a water-immiscible compound of formula(10) with carbon dioxide, CS₂ or COS in the presence of water maycomprise:

preparing an aqueous solution of carbon dioxide, CS₂ or COS in water;and mixing the aqueous solution with a water-immiscible compound offormula (10).

Alternatively, the contacting of a water-immiscible compound of formula(10) with carbon dioxide, CS₂ or COS in the presence of water maycomprise:

dissolving carbon dioxide, CS₂ or COS in a water-immiscible compound offormula (10) to provide a non-aqueous liquid; and

mixing the non-aqueous liquid with water.

The salt of formula (20) is water-soluble and can therefore form asingle-phase aqueous solution when dissolved in water. This is anextremely advantageous property which can be used to separate a compoundof formula (10) from a substance which is miscible with the compound offormula (10), but is water-immiscible, by converting the compound offormula (10) to a water-soluble salt of formula (20).

Furthermore, the water-soluble salt of formula (20) may be convertedback into a water-immiscible compound of formula (10) by removal of agas that liberates hydrogen ions from the solution. This is advantageousbecause it allows the re-use of the compound of formula (10) that iswater-immiscible.

Formulas (10), (20), (3) and (30) show an anion as ⁻E₃CH, where E may beO, S or both O and S. That is, when all three E are O, the anion isbicarbonate (also called hydrogen carbonate). When two E are O and one Eis S, the anion is hydrogen thiocarbonate. When E is one O and two S,the anion is hydrogen dithiocarbonate. When all three E are S, the anionis hydrogen trithiocarbonate. It is to be understood that anions presentin the system are expected also to include [CE₃]²⁻, known as carbonate,thiocarbonate, dithiocarbonate, or trithiocarbonate. In mostembodiments, where the pH is close to neutral, the concentration of[CE₃]²⁻ will be small compared to the concentration of ⁻E₃CH. However,in some embodiments, at higher pH, the concentration of [CE₃]²⁻ willapproach or even surpass the concentration of ⁻E₃CH. For example, such asituation may arise in applications requiring higher pH. For anotherexample, such a situation may arise during a stage in the removal of CE₂when the removal of CE₂ is incomplete but the pH has risen sufficientlyduring the process to allow the concentration of [CE₃]²⁻ to approach oreven surpass the concentration of ⁻E₃CH.

A gas that liberates hydrogen ions may be expelled from a solution bysimple heating or by placing the solution under reduced pressure (e.g.,less than 1 atm). Alternatively and conveniently, a nonreactive gas maybe employed to expel a gas that liberates hydrogen ions from a solution.Such a nonreactive gas is referred to herein as a “flushing gas”. Thisshifts the equilibrium from ionic form to hydrophobic liquid (amidine oramine). In certain situations, especially if speed is desired, both aflushing gas and heat can be employed.

Preferred flushing gases are N₂, air, air that has had its carbondioxide component substantially removed, and argon. Less preferrednonreactive (flushing gases) are those gases that are costly to supplyand/or to recapture, where appropriate. However, in some applicationsone or more flushing gases may be readily available and therefore addlittle to no extra cost. In certain cases, flushing gases are lesspreferred because of their toxicity, e.g., carbon monoxide.

Air is a particularly preferred choice as a flushing gas according tothe invention, where the CO₂ level of the air (today commonly 380 ppm)is sufficiently low that an ionic form (am idinium or ammonium salt) isnot maintained in its salt form. Untreated air is preferred because itis both inexpensive and environmentally sound. In some situations,however, it may be desirable to employ air that has had its carbondioxide component substantially removed as a flushing gas. By reducingthe amount of CO₂ in the flushing gas, potentially less salt/amidine oramine may be employed. Alternatively, some environments may have airwith a high CO₂ content, and such flushing gas would not achievecomplete switching of ionic form to hydrophobic amidine or amine form.Thus, it may be desirable to treat such air to remove enough of its CO₂for use as a trigger.

In a preferred embodiment, in the presence of water and carbon dioxide,an amidine compound of formula (1) that is water-immiscible, converts toan amidinium bicarbonate, depicted as a salt of formula (3) below,

where n, R¹, R², R³, and R⁴ are as defined above.

The salt which can be an amidinium bicarbonate compound may be a solidor a liquid. It will be apparent that at least a molar equivalent ofwater is required to react with the carbon dioxide to provide thecarbonic acid to protonate the nitrogen atom of the imino group of theamidine to form the amidinium cation. In embodiments where a certainamidinium bicarbonate of formula (3) is a solid and not a liquid, morethan a molar equivalent of water (relative to the amidine compound offormula (1) that is water-immiscible) is added to ensure the completedissolution of the amidinium bicarbonate in the aqueous phase afterswitching. In some embodiments, the amount of water is 1 or more volumeequivalents relative to the amidine. In certain embodiments, isolationof amidinium bicarbonate as a solid is possible by controlling theamount of water present.

Such amidines are more stable in acidic aqueous solution becausehydroxide attack on the amidinium cation is the primary mechanism forhydrolytic degradation. Consequently, there should be no significantdegradation of the amidinium salt when it is dissolved in carbon dioxidesaturated water (due to the presence of carbonic acid). When the salt isconverted back to the amidine compound of formula (1) that iswater-immiscible, it separates out of the water. Therefore degradationof the compound of formula (1) by hydrolysis should not be significant.This means that the amidines disclosed herein should be suitable forindustrial application, and repeated re-use, as a result of theirstability.

In a preferred embodiment, in the presence of water and carbon dioxide,an amine compound of formula (10) that is water-immiscible, converts toan ammonium bicarbonate, depicted as a salt of formula (30) below,

where n, R¹, R², R³, and R⁴are as defined above.

The ionic form which can be an ammonium bicarbonate compound may be asolid or a liquid. It will be apparent that at least a molar equivalentof water is required to react with the carbon dioxide to provide thecarbonic acid to protonate the nitrogen atom of the amine to form theammonium cation. In embodiments where a certain ammonium bicarbonate offormula (30) is a solid and not a liquid, more than a molar equivalentof water (relative to the amine compound of formula (10) that iswater-immiscible) is added to ensure the complete dissolution of theammonium bicarbonate in the aqueous phase after switching. In someembodiments, the amount of water is 1 or more volume equivalentsrelative to the amine. In certain embodiments, isolation of ammoniumbicarbonate as a solid is possible by controlling the amount of waterpresent.

In certain embodiments of compounds of formula (10) at least one of R⁵,R⁶ or R⁷ are substituted by an amino moiety (as discussed above). Suchcompounds are diamines, triamines, or polyamines. In some embodiments,polyamines are preferred since less contamination by residual solventoccurs in the hydrophobic material that is isolated when the switchablehydrophilic solvent is converted to its hydrophilic form (see Example2). Although not wishing to be bound by theory, the inventors providethe following description of why polyamines lead to less contamination.

In some embodiments, it may be advantageous to use a switchablehydrophilicity solvent that has more than one basic nitrogen atom, suchas a diamine or a triamine. There are at least two potential advantagesof such a compound over one having only one basic nitrogen atom. First,a compound with more than one basic nitrogen is likely to be a heaviercompound and therefore less volatile. It will therefore likely be lessodorous (e.g., smelly) than a compound with only one basic nitrogen.Second, a compound with more than one basic nitrogen would be expectedto be more readily separated by carbonated water from a hydrophobicliquid such as an oil. More ready separation is expected for thefollowing reason. Complete protonation of an amine switchablehydrophilicity solvent by carbonated water is not likely becausecarbonic acid is not a sufficiently strong acid. Therefore a switchablesolvent having only one basic nitrogen atom, when it is incompletelyprotonated by the carbonated water, will exist primarily as a monocationand in small amounts as its neutral form. The neutral form is likely topartition primarily into a hydrophobic phase rather than into carbonatedwater. Thus if the carbonated water only protonates the amine to theextent of, say, 96%, then at least 4% of the amine remains in thehydrophobic phase rather than in the carbonated water phase. Incontrast, a switchable solvent that is, for example, a diamine, whenincompletely protonated by carbonic acid, would consist primarily as adication with small amounts of the monocation and very small amounts ofthe neutral form. Thus, if it is assumed that only the neutral formwould have a tendency to partition into the hydrophobic phase, theamount of switchable solvent remaining in the organic phase would bevery small and on the order of the amount of the diamine that remainsuncharged. This amount must mathematically be smaller than the amount ofneutral species in the case of an amine containing only a single basicnitrogen.

The optimum logP range expected to give the desired phase behaviour(meaning that the solvent is miscible with carbonated water and notmiscible with non-carbonated water) has already been mentioned formonoamines). The inventors expect that the appropriate range of logP forcompounds having more than one basic nitrogen atom, such as diamines,may be different and possibly somewhat higher than the appropriate rangefor monoamines, although the ranges may overlap. A higher range for, forexample, diamines is expected because the diamines, when fullyprotonated, will have two hydrophilic cationic sites containinghydrogen-bonding acidic protons and two hydrophilic bicarbonate counteranions. In contrast, a monoamine, when fully protonated, will have onlyone hydrophilic cationic site and only one bicarbonate anion. Thereforea higher logP, indicating that the compound would be too hydrophobic toserve as a monoamine switchable hydrophilicity solvent, might beacceptable in a switchable hydrophilicity solvent having more than onebasic nitrogen atom because the extra hydrophobicity indicated by thehigh logKow would be overcome by the extra hydrophilicity of the extracationic sites and extra bicarbonate anions.

The following examples are offered: Me₂NCH₂CH₂CH₂CH₂NMe₂ is predicted tohave a logP of 0.9 and is not a switchable hydrophilicity solventbecause it is miscible with water even in the absence of CO₂. It istherefore too hydrophilic. Et₂NCH₂CH₂CH₂CH₂NEt₂ andEtPrNCH₂CH₂CH₂CH₂NEtPr are predicted to have logP values of 2.5 and 3.4,respectively, and are switchable hydrophilicity solvents because theyare immiscible with water in the absence of CO₂ and miscible with waterin the presence of CO₂. Therefore, they have logP values within thecorrect range for diamines to function as switchable hydrophilicitysolvents. Pr₂NCH₂CH₂CH₂CH₂NPr₂ is predicted to have a logP of 4.4 and isnot a switchable hydrophilicity solvent because it is immiscible withwater even in the presence of CO₂. It is therefore too hydrophobic. Theinventors note that the logP for a diamine must be greater than 0.9 andless than 4.4, and note that 2.5 and 3.4 are acceptable values. Theexact range that is preferred for a diamine has not yet been identifiedby the testing of further examples. The logP values that are appropriatefor triamines may be even greater than those considered acceptable fordiamines.

In some embodiments, addition of a small amount of piperazine furtherincreases the rate of conversion of a switchable hydrophilicity solventto its ionic form. In studies conducted by the inventors using acompound of formula (10), specifically dimethylcyclohexylamine (5 mL),and water (5 mL) at room temperature and a CO₂ flow rate of 100 m L/minthrough a fritted tube, it was found that in the absence of piperazine,the time of CO₂ bubbling for phase merge was 35 minutes. In the presenceof an absorption activator, specifically 10 wt % piperazine, the time ofCO₂ bubbling to phase merge was only 20 minutes. Although notexperimentally shown, the inventors expect that piperazine would have asimilar absorption activating effect for compounds of formula (1). Asimilar improvement in CO₂ capture for aqueous solutions of tertiaryamines was reported by Dubois (Chem. Eng. Tech. 32(5): 710 (2009)).

In some embodiments of the invention, the switchable hydrophilicitysolvent in its neutral form may be lipophilic or oleophilic, forexample, dimethylcyclohexylamine, Et₂NCH₂CH₂CH₂CH₂N Et₂.

An aspect of this invention provides a method of extracting a selectedsubstance from a starting material or starting materials that comprisethe selected substance. In some embodiments, the selected substance iswater-immiscible. For instance the starting material may be a solidimpregnated with the selected substance or a liquid mixture of theselected substance and a hydrophilic liquid or the selected solidsubstance containing undesired gas bubbles. The selected substance maybe a hydrophobic liquid such as an oil or a hydrophobic solid such as awax or polymer. The selected substance should be miscible or soluble ina switchable hydrophilicity solvent, which may be water-immisciblecompound of formula (1) or formula (10), and thereby be readilyseparable from the rest of the starting material.

For instance, if a selected substance is a hydrophobic liquid, amiscible mixture can be formed by mixing the selected substance with aswitchable hydrophilicity solvent, which may be a water-immisciblecompound of formula (1) or formula (10), which water-immiscible compoundacts as a hydrophobic liquid solvent. If the selected substance is ahydrophobic solid, it can be dissolved in a water-immiscible compound offormula (1) or formula (10), which water-immiscible compound acts as ahydrophobic liquid solvent.

The miscible mixture or solution of the selected substance andswitchable hydrophilicity solvent is a single-phase liquid. Thus, it ispossible to isolate the miscible mixture or solution from any furthercomponents of the starting material or starting materials which are notsoluble or miscible with the single-phase liquid. For instance, if sucha further component is a solid (e.g., residual soy bean flakes where thesoy oil has been extracted/removed), it can be separated from thesingle-phase liquid by filtration. If such a further component is aliquid which is immiscible with the single-phase liquid, this componentcould be separated by decanting. If such a further component is a gas,this component could be liberated during the dissolution of the selectedsubstance or with subsequent heating or otherwise degassing (e.g.,reduced pressure conditions) of the solution.

A selected substance, such as a solute, which is soluble in a switchablehydrophilicity solvent, which may be a water-immiscible compound offormula (1) or formula (10), or a liquid, which is miscible with awater-immiscible compound of formula (1) (or formula (10)), can beseparated from a compound of formula (1) (or formula (10)) by switchingthe hydrophilicity of the compound of formula (1) (or formula (10)).When a water-immiscible compound of formula (1) (or formula (10)) hasbeen converted into its ionic form (salt) of formula (2) (or formula(20)), the selected substance, such as the solute or liquid may separateas a distinct phase. This can occur if the selected substance isimmiscible with or insoluble in either an ionic liquid of formula (2)(or formula (20)) or an aqueous solution of a salt of formula (2) (orformula (20)). After switching, two phases can be formed, an aqueousphase comprising an ionic form (salt) of formula (2) (or formula (20))and a non-aqueous phase comprising a selected substance. The phase ofselected substance, such as a solid precipitate or hydrophilic liquidlayer, may then be separated from the aqueous solution of thehydrophilic second form of the solvent by, for example, decanting,filtering, and centrifuging. Similarly, if the amount of water iscontrolled so that the ionic compound of formula (2) (or formula (20))forms as a solid and the selected substance is a liquid, then the liquidphase of the selected substance can be separated from the solid ioniccompound of formula (2) (or formula (20)) by filtration.

This method of extracting a selected substance is particularly effectiveif the selected substance is hydrophobic and miscible/soluble in aswitchable hydrophilicity solvent, which may be a water-immiscibleamidine compound of formula (1) or a water-immiscible amine compound offormula (10). An example of this embodiment of the invention ispresented in FIG. 3B which shows extraction of soybean oil from soybeanflakes using a water-immiscible amidine of formula (1) as solvent (seealso Example 2A-C). This figure shows that when soy flakes are mixedwith amidine (“B”), soybean oil (“oil”) is extracted from the flakes andthe two liquids are miscible (“B+oil”). The soybean flakes may then beseparated from the B+oil mixture by filtration. As discussed in workingexample 2, soybean oil (“oil”) was experimentally shown to be misciblewith a water-immiscible liquid amidine of formula (1). Further, soybeanoil was isolated from the B+oil mixture by switching the solvent fromits hydrophobic form to its amidinium bicarbonate hydrophilic form (seeFIG. 3 b). Specifically, as discussed in Example 2, the mixture wascontacted with carbon dioxide in the presence of water to switch theliquid amidine to its water soluble amidinium bicarbonate form(hydrophilic form) as shown by formula (3). The contacting was carriedout by treating a miscible mixture with carbonated water or adding waterto form a two-phase mixture of an aqueous phase and a non-aqueous phasecomprising a liquid amidine of formula (1) that is water-immiscible andsoy oil and then actively exposing the two-phase mixture to carbondioxide. The soy oil then formed a non-aqueous layer and the amidiniumbicarbonate formed an aqueous layer comprising a solution of the salt inwater (“[BH][O₂COH] in water”). The non-aqueous and aqueous layers areimmiscible and formed two distinct phases, which can then be separatedby, e.g., decantation. Once separated, the non-aqueous and aqueouslayers provide an isolated non-aqueous phase comprising soybean oil andan isolated aqueous phase comprising the hydrophilic amidiniumbicarbonate form of the switchable solvent. In this way, the solvent isseparated from the soy oil without distillation.

The amidinium bicarbonate salt of formula (3) in the aqueous phase wasswitched back to its hydrophobic form (amidine compound of formula (1)that is water-immiscible) by removal of carbon dioxide from the solutione.g., by heating or degassing. The amidine compound of formula (1) thatis water-immiscible separated from the water to provide a non-aqueouslayer separate from the aqueous phase. The amidine compound of formula(1) that is water-immiscible was then separated from the water by, e.g.,decanting to isolate a non-aqueous phase comprising the hydrophobicamidine, which can then be reused to treat more soy flakes.

Thus switchable hydrophilicity solvents provide a low energy, lowpollution alternative to current technology for extractions such assoybean oil extraction. Currently, the solvent used for soy bean oilextraction from soy bean flakes is hexane. The use of hexane as asolvent is undesirable because of its neurotoxicity and high volatilityeven at room temperature. The high volatility of hexane, or any othersolvent that is to be removed by distillation, is necessary for thedistillation but is most regrettable in terms of health andenvironmental impact. Volatile solvents are easily partially lost byevaporation, and thus contribute to smog formation, ground-level ozoneformation, high flammability, high insurance costs, and workerinhalation hazards such as toxicity, neurotoxicity, carcinogenicity,mutagenicity, teratogenicity, and short and long term damage to vitalorgans. The identification of switchable hydrophilicity solvents, whichcan be removed without distillation, means that volatile solvents can beavoided.

Another example that is similar to extraction of soybean oil fromsoybean flakes is extraction of algae oil from algae. Algae oil can beused in biodiesel production. Switchable hydrophilicity solvents areuseful for dissolving algae oil. The liquid mixture, which includesswitchable solvent and dissolved oil, is then readily separated fromsolid algae by. e.g., decantation or filtration. The oil can then beseparated from the switchable solvent by placing the liquid mixture incontacting with carbon dioxide in the presence of water. Under theseconditions the solvent switches to its water miscible form and migratesto a hydrophilic liquid layer that is distinct from the hydrophobiclayer, which includes the algae oil. The algae oil is then readilyseparable from the hydrophilic layer by. e.g., decantation.

During off shore drilling a large amount of waste is generated in theform of drilling fines. Drilling fines are typically mixtures of rock,dispersants, wetting agents, emulsifiers, lubricants and drilling fluidand are usually cleaned/treated before disposal. In the case of offshoredrilling sites, this contaminated rock is currently transported from theoffshore oilrig to the mainland before treatment. Such samples generallycontain 10-40 wt % impurities (e.g., drilling fluid(s), oil, etc.) whenthey are initially brought onto the oilrig. In order for the mass to bedisposed of it must contain less than 5% impurity. If the waste could betreated on the oilrig it and disposed over board it would greatly reducethe environmental impact of the process. As described in Example 9,switchable hydrophilicity solvent technology could clean (i.e., removecontaminant(s)) the contaminated rock samples and recover contaminantsfor reuse in other applications. As described in Example 10, studiesusing a conventional solvent, specifically hexanes, to removecontaminants showed the obtained sample of contaminated rock obtainedfrom drilling fines to be 19 wt % fluids. When a sample of thiscontaminated rock was mixed with a switchable hydrophilicity solvent offormula (10), specifically N,N-dimethylcyclohexyl-amine, filtered, anddried under an air flow it resulted in a dry sand/rock mixture. An oilyfluid was then isolated from the filtrate. When the amine/fluid mixturewas combined with the aqueous layer and bubbled with CO₂, a clear,yellow oil-like layer was obtained. This layer corresponded to a valueof 17 wt % of the original contaminated rock sample. Accordingly, theSHS was able to effectively remove and recapture the contaminant(drilling fluid, oil, etc.) from the sample of drilling fines.

The invention further provides a method for maintaining or disruptingmiscibility of two liquids where one of the two liquids is a reversibleswitchable hydrophilicity solvent comprising an aqueous solution of asalt of formula (2) or formula (20). When a trigger is applied, theswitchable hydrophilicity solvent's properties change to becomehydrophobic (a water-immiscible compound of formula (1) or formula (10))and the newly-immiscible liquids separate. An embodiment of theinvention provides a switchable hydrophilicity solvent that can bereversibly and readily switched between immiscible hydrophobic liquid(compound of formula (1) or formula (10) that is water-immiscible) andwater and an aqueous solution of the hydrophilic form of the solvent(salt of formula (3) or formula (30)) by applying or removing CO₂.

Referring to FIG. 1, a chemical scheme and schematic drawing are shownfor a switchable hydrophilicity solvent system of amidine and water.Such a system is further discussed in relation toN,N,N′-tripropylbutyramidine (R1═R2═R3═R⁴=propyl) andN,N,N′-tributylpentanamidine (R¹═R²═R³═R⁴=butyl), which are examples ofwater-immiscible compounds of formula (1), in the Examples below. Thechemical reaction equation shows a substituted amidine (hydrophobicform) and water on the left hand side and amidinium bicarbonate (ionicand thus hydrophilic form) on the right hand side. This reaction can bereversed, as indicated. The schematic also shows the same reactionwherein the two-phase mixture of the compound of formula (1) that iswater-immiscible (amidine) and water is on the left side under a blanketof N₂. The aqueous solution of the salt comprising amidinium bicarbonateis shown on the right side under a blanket of carbon dioxide.

Referring to FIG. 2, the hydrophilicity/hydrophobicity of variousamidine and guanidine liquids is provided by indicating calculated logPvalues for each liquid.

Referring to FIG. 3A a comparison of the polarity of water-saturatedN,N,N′-tributylpentanamidine, shown as an open square, and an aqueoussolution of N,N,N′-tributylpentanamidinium bicarbonate, shown as a blacksquare, as measured by the maximum wavelength of absorption in nm of thesolvatochromatic dye Nile Red, with other solvents and switchablesolvents is presented.

Referring to FIG. 3B, a method of separating a selected liquid (“oil”)from a mixture comprising a selected liquid as disclosed herein ispresented. In this embodiment the selected liquid is soy oil and themixture comprising the selected liquid includes soy flakes.

Referring to FIGS. 4A and 4B, ¹H NMR spectra ofN,N,N′-tripropylbutyramidine and N,N,N′-tripropylbutyramidiniumbicarbonate in D₂O at 400 MHz are shown.

Referring to FIGS. 5A and 5B, ¹³C NMR spectra ofN,N,N′-tripropylbutyramidine and N,N,N′-tripropylbutyramidiniumbicarbonate in D₂O at 100 MHz are shown.

Referring to FIGS. 6A and 6B, IR spectra of N,N,N′-tripropylbutyramidineand N,N,N′-tripropylbutyram idinium chloride between potassium bromideplates are shown.

Referring to FIGS. 7A and 7B, ¹H NMR spectra ofN,N,N′-tributylpentanamidine and N,N,N′-tributylpentanamidiniumbicarbonate in D₂O at 400 MHz are shown.

Referring to FIGS. 8A and 8B, ¹³C NMR spectra ofN,N,N′-tributylpentanamidine and N,N,N′-tributylpentanamidiniumbicarbonate in D₂O at 100 MHz are shown.

Referring to FIGS. 9A and 9B, IR spectra of N, N,N′-tributylpentanamidine and N,N,N′-tributylpentanamidinium chloridebetween potassium bromide plates are shown.

Referring to FIG. 10, multiple ¹H NMR spectra from aN,N,N′-tributylpentanamidine/N,N,N′-tributylpentanamidiniumbicarbonate/D₂O switchability study carried out in methanol-d₄ at 400MHz with a sodium acetate internal standard are shown. This is discussedin Example 1D below.

Referring to FIG. 11, multiple ¹H NMR spectra in CDCl₃ at 400 MHz of anextraction study using N,N,N′-tributylpentanamidine with soybean oil(top), soybean oil and N,N,N′-tributylpentanamidine (middle) and soybeanoil after switching (bottom) are shown. The spectra are discussed inExample 2 below.

Referring to FIG. 12, a chemical scheme and schematic drawing are shownfor a switchable hydrophilicity solvent system of amine and water. Sucha system is further discussed in relation to N,N-dimethylcyclohexane andN-ethylpiperidine, which are examples of water-immiscible compounds offormula (10), in the Examples below. The chemical reaction equationshows an amine (hydrophobic form) and water on the left hand side andammonium bicarbonate (ionic and thus hydrophilic form) on the right handside. This reaction can be reversed, as indicated. The schematic alsoshows the same reaction wherein the two-phase mixture of the compound offormula (10) that is water-immiscible (amine) and water is on the leftside under a blanket of N₂. The aqueous solution of the salt comprisingammonium bicarbonate is shown on the right side under a blanket ofcarbon dioxide.

Referring to FIG. 13, the hydrophilicity/ hydrophobicity of variousamine liquids is provided by indicating calculated log P values for eachliquid. The compounds are shown segregated into three groups. Those onthe left are miscible with water under air or nitrogen and are thereforenot switchable hydrophilicity solvents under experimental conditionsdescribed herein. Those on the right are immiscible with water evenafter CO₂ gas is bubbled through the liquid mixture and are thereforenot switchable hydrophilicity solvents under experimental conditionsdescribed herein. It should be understood that under differentconditions, such as higher partial pressure of CO₂ these compounds maybecome miscible. Those in the middle section of the figure areimmiscible with water under air or nitrogen but become miscible withwater after CO₂ is bubbled through the liquid mixture and are thereforeswitchable hydrophilicity solvents under experimental conditionsdescribed herein.

Referring to FIG. 14, a plot is shown comparing the efficiency of ofsoybean oil extraction by a SHS system using N,N-dimethylcyclohexylamineat 25° C. and 60° C., versus extraction using hexanes at 60° C. Asshown, SHS systems are comparably effective, while offering the addedadvantage of eliminating the need for costly andenvironmentally-unfriendly distillation of the solvent.

Referring to FIG. 15, a schematic depiction is shown of a system of theinvention wherein in the left-most beaker is shown a switchablehydrophilicity solvent (SHS) that is a liquid. When the SHS is exposedto an aqueous solution (e.g., water, salty water, an aqueous solutionthat includes a dye for analytical tracking to monitor process) atwo-layer liquid mixture is formed, as shown in the beaker at the leftof centre. When this two-layer aqueous liquid mixture is exposed to CO₂it becomes a single-layer aqueous liquid mixture as shown in the beakerat the right of centre. When this single-layer aqueous mixture has CO₂expelled by exposure to a flushing gas (e.g., air), or heat, or bothheat and a flushing gas, CO₂ is dispelled from the single-layer liquidmixture, it reverts to a two-layer liquid mixture. As shown by the largearrows, the two layer solutions can be separated from one another, e.g.,by decantation, and can be reused in the system. As noted above, in someembodiments the aqueous layer is a salty water solution. Salt water maybe an advantage in obtaining a “clean” separation of the two layersand/or diminishing formation of an emusion.

Referring to FIG. 16, a schematic depiction is shown of a system of theinvention for removing a hydrophobic contaminant (e.g., cleaning) fromparticles of contaminated solid, wherein in the left-most beaker isshown (i) a switchable hydrophilicity solvent (SHS) that is awater-immiscible liquid, and (ii) suspended particles of solid that aredepicted, for example, as being coated in a hydrophobic contaminantmaterial. The contaminant dissolves in the SHS, and the clean particlescan be recovered, e.g., by filtration (as shown in the lower vial).Following removal of the clean particles, the filtrate SHS can be mixedwith an aqueous solution as shown in the beaker that is second from theleft. Here, a two-layer liquid mixture is shown, the top layer is SHStogether with the dissolved contaminant, while the bottom layer is anaqueous solution. Upon exposure to CO₂, this two-phase liquid mixturechanges to a different two-phase liquid mixture. Specifically, uponexposure to CO₂ in the presence of water, the SHS is switched to itsprotonated form, which is miscible with the aqueous solution and hasmigrated to the aqueous layer and so the volume of the aqueous layer hasincreased. The hydrophobic contaminant, which is no longer solubilizedby the SHS, has formed a top layer in the third beaker from the left.The contaminant is therefore isolatable from the SHS and aqueous layerby e.g., decantation (as shown in the upper vial). When the contaminanthas been removed, the protonated form of the SHS and the aqueous layercan be separated by triggering the water-miscible form of the SHS toswitch to the water-immiscible form of the SHS. This is shown byexposing the single-layer aqueous liquid mixture of the third beakerfrom the left to air. Thus the right-most beaker holds a two-phaseliquid mixture. The SHS and the aqueous layer can then be reused asshown by the large arrows. FIG. 16 is intended to represent a system forremoving hydrophobic contaminant(s) that is suitable for removal of dirtor odorous compound(s) from plastics (e.g., HDPE, PVC) (see Example 11),removal of drilling fluids and oil from drilling fines (see Example 10),removal of oil from oil sands (see Example 9), degreasing, andremediation of soil contaminated by hydrophobic material.

Referring to FIG. 17, a schematic is shown of a system of the inventionfor extraction of a selected material (that may be a compound or a groupof compounds) from a solid. In the left-most beaker is shown (i) aswitchable hydrophilicity solvent (SHS) that is a water-immiscibleliquid, and (ii) suspended particles of solid that are impregnated witha hydrophobic selected material. For example, such particles may beseeds impregnated with seed oil, nuts impregnated with nut oil, soyflakes impregnated with soy oil, etc. The hydrophobic selected materialis soluble in the SHS, and the barren particles (e.g., oil-less nutflakes, oil-less soy flakes, etc.) can be removed by filtration (asshown in the lower vial). Following removal of the barren particles, thefiltrate (SHS plus extract) can be mixed with an aqueous solution asshown in the beaker that is second from the left. Here, a two-layerliquid mixture is shown, the top layer is SHS together with theextracted selected material, while the bottom layer is an aqueoussolution. Upon exposure to CO₂, this two-phase liquid mixture changes toa different two-phase liquid mixture. Specifically, upon exposure to CO₂in the presence of water, the SHS is switched to its protonated form,which is miscible with the aqueous solution and it has migrated to theaqueous layer, and so the volume of the aqueous layer has increased. Thehydrophobic extract, which is no longer solubilized by the SHS, hasformed a top layer as shown in the third beaker from the left. Theextract is therefore isolatable from the SHS and from the aqueous layerby, e.g., decantation (as shown in the upper vial). When the extract hasbeen removed, the protonated form of the SHS and the aqueous layer canbe separated by triggering the water-miscible form of the SHS to switchto its water-immiscible form. This is shown by exposing the single-layeraqueous liquid mixture, shown in the bottom layer of the third beakerfrom the left, to air. Thus the right-most beaker holds a two-phaseliquid mixture of the SHS and the aqueous layer. These layers can thenbe separated by, e.g., decantation, and reused in the appropriate stepsas shown by the large arrows. This extraction example is suitable forextraction of seed oils, bean oils, nuts oils, algae oils, and plasticmade by bacteria. Such a system for extraction of a selected hydrophobicmaterial is also suitable for extraction of bitumen from oil sands.

Referring to FIG. 18, a schematic depiction is shown of a system of theinvention for isolation of a component in a chemical synthesis. In theleft-most beaker is shown (i) a switchable hydrophilicity solvent (SHS)that is a water-immiscible liquid, and (ii) dissolved reagents (A and B)of chemical reaction A+B→C. In no specified order, the chemical reactionoccurs and an aqueous liquid is added. Accordingly, reaction product Cis now depicted as dissolved in the SHS (shown as top layer of beakerthat is second from the left). Upon exposure to CO₂ in the presence ofwater, the two-phase liquid mixture in the beaker that is second fromthe left changes to a different two-phase liquid mixture shown in thebeaker that is third from the left. Specifically, upon exposure to CO₂in the presence of water, the SHS switched to its protonated form. Inthis form, it is miscible with the aqueous solution, and it has migratedto the aqueous layer. Accordingly, the volume of the aqueous layer hasincreased. In this example, reaction reagents A and B are now also inthe aqueous layer. Notably, the reaction product C forms a hydrophobiclayer and so it is isolatable from the aqueous layer by, e.g.,decantation (as shown in the upper capped vial). When this hydrophobiclayer has been removed, the protonated form of the SHS and the aqueouslayer can be separated by triggering the water-miscible form of the SHSto switch to its water-immiscible form. This is shown by exposing thesingle-layer aqueous liquid mixture, shown in the bottom layer of thethird beaker from the left, to air. Thus the right-most beaker holds atwo-phase liquid mixture of the SHS and solubilised reagents A and B,and the aqueous layer. These layers can then be separated by, e.g.,decantation and reused in the appropriate steps as shown by the largearrows. This figure is shown to depict a system suitable for isolationof a component of a chemical reaction. The isolated component may be achemical product, or it may be a side product. This system allows forchemical separation, which may be product isolation, withoutdistillation.

Referring to FIG. 19, a schematic depiction is shown of a system of theinvention for isolation of a plastic from a mixture of plastics. In theleft-most beaker is shown a mixture of plastics including polystyrene(PS), polyvinylchloride and polyethylene terephthalate. Moving to theright, a switchable hydrophilicity solvent (SHS) that is awater-immiscible liquid, is added and the PS dissolves. Remainingundissolved solids are then removed by filtration to give solids thatare polyvinylchloride and polyethylene terephthalate and a liquidfiltrate that is SHS and dissolved PS. An aqueous solution is added tothe filtrate and a two-layer liquid mixture is shown in the third beakerfrom the left. This two layer liquid mixture is exposed to CO₂ in thepresence of water, and a single-layer liquid mixture is formed that isan aqueous solution of protonated SHS. Since PS does not dissolve inaqueous solutions, solid polystyrene precipitates from this single-layeraqueous solution and is isolated by, e.g., filtration or decantation (asshown in the upper capped vial). When the single-layer aqueous mixtureis exposed to a flushing gas such as air to dispel CO₂ from the liquid,it reverts to a two-layer aqueous liquid mixture. As shown by the largearrows, the two layer solution can be separated by, e.g., decantationand reused. This schematic is provided to show a system whereinpolystyrene can be dissolved, optionally separated from other plastics,and collected. A mixture of plastics is intended to include a bale wheredifferent types of plastic are bundled together, for example, forrecycling. Notably, polystyrene dissolution and recapture is possible inthe absence of distillation. As described herein, it is also possible todissolve a polystyrene foam, thereby removing the gaseous portion of thefoam, and collect substantially pure polystyrene.

Referring to FIG. 20, a schematic is shown depicting a system of theinvention for adding a hydrophobic compound or compounds to a material.In the left-most beaker is shown a single-layer liquid that is a SHS anddissolved hydrophobic compound or compounds. Solid particles may beadded to this left-most beaker, or they may be added to the beaker thatis second from left, which holds a two-layer liquid mixture of theSHS+hydrophobic compound, and an aqueous solution. In either case wecome to the third beaker from the left which holds a two phase liquidmixture wherein the solid particles are in contact with theSHS+hydrophobic compound. The solid particles become changed and arecoated or impregnated by the hydrophobic compound. The SHS can beremoved form the solid particles by exposing the two phase mixture inthe third beaker from the left to CO₂. As shown in the fourth beakerfrom the left, the liquid becomes a single-layer liquid mixture and thechanged solid particles can be isolated by, e.g., filtration ordecantation (as shown in the upper capped vial). When the single-layeraqueous mixture is exposed to a flushing gas such as air to dispel CO₂from the liquid, it reverts to a two-layer aqueous liquid mixture. Thelayers can be separated by, e.g., decantation and reused. This system isdepicted to exemplify how a system using SHS can be employed to add dyeto textile (e.g., fabric)(see Example 12), functionalize surfaces of,for example, vesicles, or polymer beads, add corrosion inhibitor (i.e.,anticorrosion material), surface stabilizers, mordants, antioxidants,preservatives, enzymes, antigens or brighteners, and/or impregnateparticles. Impregnation of particles may be applied in the field of, forexample, drug-delivery.

As described in the working examples, several salts of formulas (2) and(3) have been formed by reacting carbon dioxide with water-immiscibleamidine compounds of formula (1) in the presence of water. Aqueousmixtures advantageously provide a rapid rate of reaction to formwater-soluble amidinium bicarbonate compounds from water-immisciblecompounds of formula (1), and allow dissolution of the amidiniumbicarbonate compounds should they be solid at reaction conditions.

Compounds of embodiments of the invention may have higher aliphatic(C₅-C₁₀) groups. Monocyclic, bicyclic, or tricyclic ring structures, mayalso be used. However, too many higher aliphatic groups may cause acompound to be waxy and non-liquid at room temperature. Preferredembodiments of the invention are liquid at room temperature. Also, asthe length of an aliphatic group increases, the difference between thehydrophobicity of a water-immiscible compound of formula (1) or offormula (10) and the hydrophilicity of its corresponding ionic form isdiminished. The larger this difference, the better the hydrophobicinteraction of a water-immiscible compound with the selected substanceto be separated, and the better the hydrophilic interaction of itscorresponding salt second form with water after switching. For thesereasons, preferred aliphatic chain length is 1 to 6. In someembodiments, the compound of formula (1) or (10) has two or moreprotonatable sites, with the result that the hydrophobicity of somewhatlonger aliphatic chains, extra rings, or other hydrophobic structuralfeatures can be overcome in the ionic form.

A compound of formula (1) or (10) having a group that includes an etheror ester moiety is also encompassed by the invention. In preferredembodiments, an aliphatic group is alkyl. Aliphatic groups may besubstituted with one or more moieties such as, for example, asubstituent is independently alkyl, alkenyl, alkynyl, aryl, aryl halide,heteroaryl, non-aromatic rings, Si(alkyl)₃, Si(alkoxy)₃, halo, alkoxy,amino, ester, amide, amidine, thioether, alkylcarbonate, phosphine,thioester, or a combination thereof. Reactive substituents such as alkylhalide, carboxylic acid, anhydride and acyl chloride are not preferred.

In other embodiments of the invention the R¹⁻⁷ groups of a compound ofthe invention may not be higher aliphatic; but instead are loweraliphatic groups, and are preferably small, nonpolar and non-reactive.Examples of such groups include lower alkyl (C₁ to C₄) groups. Preferredexamples of the lower aliphatic groups are CH₃, CH₂CH₃,CH(CH₃)_(2, C(CH) ₃)^(3,) Si(CH₃)₃, and phenyl. Monocyclic, or bicyclicring structures, may also be used. If one R group is a higher aliphaticgroup, such as hexyl or cyclohexyl, then it may be necessary for other Rgroups to be lower aliphatic groups in order to prevent the compoundfrom being so hydrophobic that the ionic form is not soluble or misciblein water.

It will be apparent that in some embodiments the substituents R¹⁻⁴ maybe selected from a combination of lower and higher aliphatic groups.Furthermore, in certain embodiments where there is only one protonatablesite in the molecule, the total number of carbon and silicon atoms inall of the substituents R¹, R², R³ and R⁴ (including optionalsubstituents) of a water-immiscible compound of formula (1) may be inthe range of 10 to 20. This provides a good balance of hydrophobicityand hydrophilicity between the two forms. In this way, a calculated logPvalue of the compound of formula (1) that is water-immiscible can beprovided in the range of about 3 to about 7.

It will be apparent that in some embodiments the substituents R⁵⁻⁷ maybe selected from a combination of lower and higher aliphatic groups.Furthermore, in certain embodiments where there is only one protonatablesite in the molecule, the total number of carbon and silicon atoms inall of the substituents R⁵, R⁶ and R⁷ (including optional substituents)of a water-immiscible compound of formula (10) may be in the range of 5to 9. This provides a good balance of hydrophobicity and hydrophilicitybetween the two forms. In this way, a calculated logP value of thecompound of formula (10) that is water-immiscible can be provided in therange of about 1.3 to about 3. In certain embodiments where there ismore than one protonatable site in the molecule, the total number ofcarbon and silicon atoms in R⁵, R⁶, and R⁷ (including optionalsubstituents) may be higher than 9, although not higher than 9 perprotonatable site, and the range of acceptable logP values may extend tohigher than 3. For amines having two protonatable sites (e.g. diamines),preliminary tests show that high end of the logP range should slightlyabove 4.

In certain embodiments, the amidine compound of formula (1) that iswater-immiscible does not have any N—H bonds. If N-H bonds are present,this will lead to an increase in the hydrophilic nature of the amidine.In order to provide an amidine that can be reversibly switched, it ispreferred to balance the presence of N—H bonds with longer chainaliphatic groups, such as higher aliphatic groups, to provide an amidinewith the desired level of hydrophobic character, i.e., an amidine whichis sufficiently hydrophobic to be water-immiscible but not sohydrophobic that the corresponding amidinium carbonate salt iswater-immiscible or water-insoluble.

In preferred embodiments, conversion of the compound of formula (1) orformula (10) that is water-immiscible to the salt is complete. Incertain embodiments, the conversion to salt is not complete; however, asufficient amount of the liquid mixture is converted to the salt form tochange the properties of the liquid and make it substantiallywater-miscible. Analogously, in some embodiments, the conversion of saltform back to the hydrophobic compound of formula (1) or formula (10)that is water-immiscible may not be complete; however a sufficientamount of the salt is converted to the hydrophobic compound of formula(1) or formula (10) that is water-immiscible and water to cause thehydrophobic compound to form a separate phase from the aqueous phase.

It should be understood that the invention further encompasses amidinesor amines that react to form salts in the presence of water and in thepresence of CO₂, CS₂, COS, or a combination thereof, as discussedherein.

Amidine compounds of formula (1) having a calculated logP value of lessthan about 3 are less preferred for use in the present invention becausethey are more hydrophilic in character such that the amidine form may bemiscible with water. However, the defining characteristic isimmiscibility in water; an amidine that is water-immiscible and yet hasa logP below 3 is still acceptable.

Hydrophobicity data for a number of amidines in hydrophobic form ispresented in FIG. 2. The amidines A-D exhibit calculated logP values inthe range of 1.2 to 2.0. This represents relatively hydrophiliccharacter. The amidines A-D are unsatisfactory for use as a switchablehydrophilicity solvent because they are insufficiently hydrophobic intheir amidine form. They were found to be soluble in water in both theirhydrophobic amidine form and their hydrophilic salt form as amidiniumbicarbonates. Since such amidines are not separable from water afterswitching from their hydrophilic to hydrophobic forms, they areunsuitable for use in the present invention.

Amidines E and F, representing N,N,N′-tripentylhexanamidine andN,N,N′-trihexylheptanamidine respectively have calculated logP values of7.8 and 9.1 respectively. The calculated logP values of further amidines(not shown in FIG. 2) have also been determined. N,N-diphenyl,N′-butylpentanamidine (compound of formula (1); R¹═R²=butyl;R³═R⁴=pentyl) has a calculated logP value of 7.0. N-butyl, N-pentyl,N′-butylpentanamidine (compound of formula (1); R¹═R²=butyl; R³,R⁴=butyl, pentyl) has a calculated logP value of 6.5. N-butyl, N-pentyl,N′-pentylhexanamidine (compound of formula (1); R¹═R²=pentyl; R³,R⁴=butyl, pentyl) has a calculated logP value of 7.4. N,N-dipentyl,N′-butylhexanamidine (compound of formula (1); R¹=butyl; R²=pentyl;R³═R⁴=pentyl) has a calculated logP value of 7.4.

Amidine compounds of formula (1) having a calculated logP value inexcess of 7 are less preferred for use in the present invention becausethey are more hydrophobic in character such that the hydrophilicamidinium bicarbonate form would be less readily miscible with water.This may increase the difficulty of separating the salt form from theselected substance it was used to take up in hydrophobic form.

In contrast, the amidines PA and BA, which representN,N,N′-tripropylbutyramidine (PA) and N,N,N′-tributylpentanamidine (BA)respectively exhibit calculated logP values in the preferred range ofabout 3 to about 7. These compounds were immiscible with water in theirhydrophobic amidine forms, but became miscible after the introduction ofa carbon dioxide trigger and water which converted them to their ionicamidinium carbonate forms.

The amidine compounds of formula (1) such as PA and BA, havinghydrophobicity in the preferred range exhibited the correct balance ofhydrophilicity distributed between hydrophobic and hydrophilic forms. Itwill be apparent that by varying the R¹⁻⁴ substituent groups, the logPvalue of the amidines can be adjusted. For instance, using lower chainlength substituents will increase the hydrophilicity of the amidine,thus lowering the calculated logP value.

Variations to the structure of compounds PA and BA are well within theskill of the person of ordinary skill in the art pertaining to theinvention. These include minor substitutions, varying the length of ahydrocarbon chain, and the like.

Those amidines with logP values in the region of greater than 3 to lessthan 5 are already relatively hydrophilic (in their amidine form), suchthat a substantially incomplete switching reaction is sufficient forthem to be rendered water-miscible. In addition, because of the greaterhydrophilic character of these amidines, greater concentrations mayremain in the aqueous phase after the hydrophilic amidinium form isswitched back to the hydrophobic amidine. When the hydrophilic amidiniumform is switched to the hydrophobic amidine form, a substantial amountmust be converted (but not necessarily complete conversion) before aphase separation of the amidine from water is observable.

In the case of embodiments of the invention that involve amidines withlogP values in the region of 5 to 7, which are relatively hydrophobic intheir amidine form, the switching reaction to form the hydrophilic formmust be substantially complete before a single-phase is observable. Itwill be apparent that this is not a kinetic barrier, but one based uponthe relatively hydrophobic nature of the amidine. Also for suchembodiments, when the hydrophilic amidinium form is switched back to thehydrophobic amidine form, substantially incomplete conversion to theamidine form will be sufficient for a phase separation to be observable.In addition, because of the greater hydrophobic character of theseamidines, lower concentrations may remain in the aqueous phase after thehydrophilic am idinium form is switched back to the hydrophobic amidine.

Amine compounds of formula (10) having calculated logP values of lessthan about 1.3 are less preferred for use in the present inventionbecause they are more hydrophilic in character such that the amine formmay be miscible with water. However, as described herein, immiscibilityin water is a defining characteristic; that is an amine that iswater-immiscible and yet has a logP below 1.3 is still be acceptable.

Hydrophobicity data for a number of amines in hydrophobic form ispresented in FIG. 13. The amines shown in the left column of the figurehad calculated logP values in the range of −1.5 to 1.2. This representsrelatively hydrophilic character. These amines are unsatisfactory foruse as switchable hydrophilicity solvents because they areinsufficiently hydrophobic in their amine form. Experimentally, theywere found to be soluble in water in their hydrophobic amine form. Sincesuch amines are not separable from water after switching from theirhydrophilic to hydrophobic forms, they are unsuitable for use in thepresent invention.

Amines shown in the right section of FIG. 13 have calculated logP valuesof 2.2 to 9.5 respectively. This section shows compounds whose ionicforms have been shown experimentally to be immiscible with water. Theionic form of a switchable hydrophilicity solvent will naturally be morehydrophilic than the non-ionic form, but if the ionic form of aparticular amine is not sufficiently hydrophilic (i.e., it is immisciblewith water) then the amine is not suitable as a switchablehydrophilicity solvent.

Amine compounds of formula (10) having a calculated logP value in excessof about 3 are less preferred for use in the present invention becausethey are more hydrophobic in character such that the hydrophilicammonium bicarbonate form would be less readily miscible with water.This may increase the difficulty of separating the salt form from theselected substance that was solubilized by the corresponding hydrophobicform of the solvent.

Amines shown in the centre column of FIG. 13, includingN-ethylpiperidine, N,N,N-triethylamine, N,N-diethyl-N-methylamine,N,N-dimethyl-N-cyclohexylamine, dimethylhexylamine, diethylbutylamine,dipropylmethylamine, N,N-diethyl-N-cyclohexylamine, andN-butylpyrrolidine had calculated logP values in a preferred range ofabout 1.3 to about 3. Experimentally, these compounds were immisciblewith water in their hydrophobic amine forms, but became water-miscibleafter being subjected to carbon dioxide in the presence of water underwhich conditions they were converted to their ionic ammonium bicarbonateforms. Accordingly, these compounds are suitable as switchablehydrophilicity solvents of the invention.

Non-limiting examples of amine compounds of formula (10) includeN-ethylpiperidine, N,N,N-triethylamine, N,N-diethyl-N-methylamine,N,N-dimethyl-N-cyclohexylamine, N,N-diethyl-N-cyclohexylamine,N,N-dimethyl-N-hexylamine, N,N-diethyl-N-butylamine,N,N-dipropyl-N-methylamine, N,N,N′,N′-tetraethylbutane-1,4-diamine andN-butylpyrrolidine. Such compounds and their corresponding ammoniumionic forms have hydrophobicity in the preferred range where theirhydrophobic uncharged form is water-insoluble or water-immiscible andtheir hydrophilic ionic forms are water-soluble or water-miscible. Byvarying the R⁵⁻⁷ substituent groups, the logP value of the amines can beadjusted. For instance, using substituents of shorter chain lengthincreases the hydrophilicity, thus lowering the calculated logP value.Notably, N,N,N-triethylamine and diethylmethylamine are quite volatile.In some embodiments, it is advantageous to have a switchablehydrophilicity solvent that is volatile and so can be readily removedfrom a mixture. In other embodiments, a switchable hydrophilicitysolvent would have low volatility so that the solvent would not have asignificant smell, it would not contribute to smog formation orinhalation hazards, and it would not suffer loss due to evaporationduring the switching process.

Variations to the structure of compounds N-ethylpiperidine,N,N-dimethylcyclohexylamine, diethylmethylamine, dimethylhexylamine,diethylbutylamine, dipropylmethylamine, triethylamine, andN-butylpyrrolidine are well within the skill of the person of ordinaryskill in the art pertaining to the invention. These include minorsubstitutions, varying the length of a hydrocarbon chain, and the like.

Those amines with logP values in the region of greater than 1.3 to lessthan 2.0 are already relatively hydrophilic (in their amine form), suchthat a substantially incomplete switching reaction is sufficient forthem to be rendered water-miscible. In addition, because of the greaterhydrophilic character of these amines, greater concentrations may remainin the aqueous phase after the hydrophilic ammonium form is switchedback to the hydrophobic amine. When the hydrophilic ammonium form isswitched to the hydrophobic amine form, a substantial amount must beconverted (but not necessarily complete conversion) before a phaseseparation of the amine from water is observable.

In the case of embodiments of the invention that involve amines withlogP values in the region of 2 to 3, which are relatively hydrophobic intheir amidine form, the switching reaction to form the hydrophilic formmust be substantially complete or close to complete before asingle-phase is observable. It will be apparent that this is not akinetic barrier, but one based upon the relatively hydrophobic nature ofthe amine. Also for such embodiments, when the hydrophilic ammonium formis switched back to the hydrophobic amine form, substantially incompleteconversion to the amine form will be sufficient for a phase separationto be observable. In addition, because of the greater hydrophobiccharacter of these amines, lower concentrations may remain in theaqueous phase after the hydrophilic ammonium form is switched back tothe hydrophobic amine.

Exposure of a 1:1 by volume mixture of two immiscible liquids,hydrophobic PA and water, to gaseous CO₂, at 1 atmosphere, caused aconversion to a hydrophilic liquid comprising an aqueous solution ofN,N,N′-tripropylbutyramidinium bicarbonate (PAB) (see FIG. 1 for thechemical scheme in which R¹⁻⁴ are propyl). NMR data for the PA/watersystem is presented in FIGS. 4 and 5 and IR data in FIG. 6. FIGS. 4A and5A show ¹H and ¹³C NMR data for PA. After switching, the detection ofthe N,N,N′-tripropylbutyramidinium bicarbonate salt was confirmed by ¹Hand ¹³C NMR as shown in FIGS. 4B and 5B.

Similarly, exposure of a 1:1 by volume mixture of two immiscibleliquids, hydrophobic BA and water, to gaseous CO₂, at 1 atmosphere,caused a conversion to a hydrophilic liquid comprising an aqueoussolution of N,N,N′-tributylpentanamidinium bicarbonate (BAB) (see FIG. 1for the chemical scheme in which R¹⁻⁴ are butyl). NMR data for thePA/water system is presented in FIGS. 7 and 8 and IR data in FIG. 9.FIGS. 6A and 7A show ¹H and ¹³C NMR data for BA. After switching, thedetection of the N,N,N′-tributylpentanamidinium bicarbonate salt wasconfirmed by ¹H and ¹³C NMR as shown in FIGS. 6B and 7B. The hydrophilicaqueous solution of BAB was converted back into hydrophobic BA and waterby heating at 80° C.

Conversion between a hydrophobic liquid (amidine) and a hydrophilicliquid (aqueous solution of am idinium bicarbonate) results in a changein the properties of the solvent. As described in the Working Examples,the hydrophobic liquid amidine (BA) was miscible with soy oil, anorganic compound. The hydrophilic liquid that was formed fromBA/water/CO₂ was immiscible with soy oil. Thus CO₂ and removal of CO₂can be used as triggers of immiscibility and miscibility, respectively.

FIG. 3A presents a comparison of the polarity of BA (hydrophobic liquidform), shown as an open square, and BAB (aqueous solution of ionicform), shown as a black square, as measured by maximum wavelength ofabsorption of a solvatochromatic dye Nile Red, with other solvents andswitchable systems. The complete experiment for BA is described inExample 3 of the Working Examples. Solvatochromatic dyes change color asa result of changes in solvent polarity. The color change is caused bythe change in the interaction of the polar ground and excited states ofthe chromophore in the dye with solvents of differing polarities.

Nile Red, when dissolved in water-saturated BA exhibits a maximumwavelength of absorption of 510 nm. It is evident from FIG. 3A that BAis less polar than many solvents such as toluene, acetone, acetonitrile(MeCN), chloroform (CHCl₃), dimethyl formamide (DMF), methanol (MeOH)and ethylene glycol. However, after switching BA to BAB with CO₂ in thepresence of water, the maximum wavelength of absorption shifts to 570nm, indicating a relatively high polarity solution having a polaritygreater than methanol and ethylene glycol. FIG. 3A further compares thechanges in polarity as a result of a CO₂ trigger of BA in a water systemwith other switchable solvents. In particular BA exhibits a dramaticchange in polarity upon switching which is significantly greater than1,8-diazabicyclo[5.4.0]undec-7-ene/propanol (DBU/ PrOH),1,1,3,3-tetramethyl-2-butylguanidine/ methanol (TMBG/MeOH),N,N-methylbenzylamine (NHMeBn) and N,N-ethylbenzylamine (NHEtBn). Thesignificant change in properties exhibited by an amidine of theinvention upon switching gives rise to a wide range of potentialapplications.

In some embodiments, the mole ratio of non-gaseous reactants (amidineand water or amine and water) is at least about equimolar. Equimolarratios can be used when the salt (amidinium bicarbonate or ammoniumbicarbonate) is a liquid. It will be apparent to one skilled in the artof the invention that when the salt form is prepared from this mixture,there will remain little or no unreacted reactant(s).

In other embodiments, the ratio of non-gaseous reactants is greater thanequimolar, i.e. the number of moles of water is greater than the numberof moles of amidine or amine. This provides additional, unreacted waterwhich is not consumed in the switching reaction. This may be necessaryto ensure that a single-phase aqueous solution of the salt is obtained.It is preferred that sufficient water is present to dissolve the saltformed after switching, should this be a solid, thereby providing asingle-phase aqueous solution. In some embodiments, the volumetric ratioof 1:1 hydrophobic liquid (amidine or amine) to water is preferred.

If insufficient water is present to solubilize a solid amidiniumbicarbonate or ammonium bicarbonate salt formed after switching,unsolubilized salt will be present as a precipitate. For instance,should the ratio of amidine (or amine) to water be equimolar,substantially all the water would be consumed in a complete switchingreaction. If the salt was a solid rather than an ionic liquid, thiswould form as a precipitate. The formation of the salt as a precipitatemay be advantageous in some circumstances because it is easilyrecoverable, for instance by filtration.

Solid salts such as bicarbonate salts of switchable hydrophilicitysolvents (e.g., see formula (2) and (20) are also convenient forshipping as they are lightweight compared to liquids. Accordingly, insome embodiments of the invention, the salt form of SHS is provided anda user prepares the neutral hydrophobic form either by heating, adding abase, adding water, adding water and heating, degassing and/or flushingwith a flushing gas to expel CO₂ from the solution. After heating,degassing or flushing an aqueous solution, two layers would be apparent,a layer comprising the hydrophobic SHS and an aqueous layer. Theselayers are isolatable by, e.g., decantation. Once isolated in thismanner, the hydrophobic SHS is obtained and is suitable for many uses asdescribed herein such as removal of contaminant, cleaning, extraction,dyeing, etc.

As described previously and depicted in FIGS. 15 to 20, thewater-immiscible hydrophobic SHS can be converted to its water-miscibleform by exposure to CO₂ in the presence of water. In this fashion,reversibly switchable systems and methods described herein are cyclicaland, like the chicken and the egg, can be entered from either startingpoint (i.e., ionic or neutral forms). For clarity herein, a startingpoint is designated; however, it is also possible to start with theother form.

In other embodiments, carbon dioxide may be substituted by carbondisulfide (CS₂) or carbonyl sulfide (COS). Carbon disulfide is notpreferred because of its flammability, its toxicity, and its negativeimpact on the environment. Carbonyl sulfide is not preferred because ofits flammability, its negative impact on human health (irritant, damageto nervous system), and its negative impact on the environment. Bothcarbonyl sulphide and carbon disulfide may produce hydrogen sulfide upondissolution in water in the presence of an amidine or amine. Hydrogensulfide is considerably more toxic than carbonyl sulphide or carbondisulfide. Nevertheless, CS₂ and COS should be capable of triggering thesame change in the switchable solvents as can CO₂.

Carbon dioxide may be provided from any convenient source, for example,a vessel of compressed CO₂(g) or as a product of a non-interferingchemical reaction. The amidines and amines of the invention are able toreact with CO₂ at 1 bar or less to trigger the switch to their saltform.

It will be understood by the skilled person that regeneration of awater-immiscible compound of formula (1) from an aqueous solution of ansalt of formula (2) (or the regeneration of a water-immiscible compoundof formula (10) from an aqueous solution of a salt of formula (20)) canbe achieved by either active or passive means. The regeneration may beachieved passively if an insufficient concentration of a trigger for theionic form form, such as carbon dioxide, is present in the surroundingenvironment to keep the amidine or amine switched to the ionic formform. In this case, a trigger such as carbon dioxide could be graduallylost from the aqueous solution by natural release. No heating, degassingor active contacting with flushing gases would be required. However,heating, degassing or contacting with flushing gases would be quickerbut may be more expensive.

A salt of formula (2) can be converted to an amidine compound of formula(1) that is water-immiscible and water by removing the carbon dioxide,for example, by exposing the mixture to a non-toxic flushing gas thatcontains substantially no carbon dioxide. Similarly, a salt of formula(20) can be so converted to a compound of formula (10). A flushing gascan be any nonreactive gas or mixture of gases that containsinsufficient CO₂ (or other gas which generates hydrogen ions) to causethe switch from an amidine to ionic form, e.g., a gas that containssubstantially no carbon dioxide. Preferably, the gas is non-toxic.Preferred gases that are substantially free of CO₂ include, for example,argon, N₂, argon, air that has insufficient carbon dioxide to switchneutral forms that are water-immiscible to ionic salts, and air with thecarbon dioxide component removed. In some cases, normal air, without anyremoval of the existing CO₂ content, will suffice as a flushing gas.Conveniently, such exposure is achieved by bubbling the gas through theaqueous solution of ionic form or by any other means of providingefficient contact between the liquid and gas phases. However, it isimportant to recognize that heating the ionic form is an alternativemethod of driving off the CO₂, and this method of converting the aqueoussolution of the ionic form form to its corresponding uncharged form thatis water-immiscible is also encompassed by the invention. In certainsituations, especially if speed is desired, both bubbling (or othermeans of providing efficient contact) and heat can be employed. Heat maybe supplied from an external heat source, preheated nonreactive gas,exothermic dissolution of gas in the aqueous solution of ionic salt, oran exothermic process or reaction occurring inside the liquid.

Similarly, if the ionic form of formula (2) or formula (20) is isolatedas a solid, then heating, degassing and/or contacting with flushing gascan be used to convert the ionic form to the hydrophobic form (amine oramidine).

In some embodiments, the amine or amidine has sufficiently lowvolatility that the process of switching back the ionic form of formula(2) or formula (20) to the amine or amidine does not result insignificant evaporation or distillation of the amine or the amidine.

In initial studies, the trigger used to expel CO₂ from solution and toswitch from ionic salt to amidine or amine was heat. However, CO₂ wasalso shown to be expelled, and the am idinium ionic salt was convertedto the amidine by contacting with a flushing gas, air (see example 1C).It is also expected that CO₂ may also be expelled from the ionic formsolution merely by passively exposing the solution to air.

Switchable hydrophilicity solvents include water-immiscible amidinecompounds of formula (1) with aliphatic portion(s) as discussed below.In certain embodiments, the amidine is peralkylated. The term“peralkylated” as used herein means that the amidine has alkyl or othergroups connected to the N atoms so that the molecule contains no N—Hbonds. This lack of N—H groups is intended to avoid the amidine form,which should be hydrophobic and water-immiscible, from becoming toohydrophilic because of the hydrogen-bond donating character of the N—Hbonds.

An advantage of switchable hydrophilicity solvents is that theyfacilitate organic syntheses and separations by eliminating the need toremove and replace solvents after each reaction step. With triggers thatare capable of causing a drastic change in the hydrophilicity of thesolvent while it is still in the reaction vessel, it may be possible touse the same solvent for several consecutive reaction or separationsteps. This would eliminate the need to remove and replace the solvent.

Reuse and recycling of solvents of the invention provide economicbenefits. The time required to switch between the hydrophilic ionicsalts of formula (2) or formula (20) and hydrophobic compounds offormula (1) or formula (10) that are water-immiscible according to theinvention is short. For instance, Example 1B shows that an incompleteswitch between a BAB ionic salt and BA compound of formula (1) can occurin 20 minutes with heating. Example 1D shows that in excess about 90% ofthe BAB ionic form can be converted back to the BA compound, which is anexample of a water-immiscible compound of formula (1), after heating for1 hour. It is advantageous to convert from hydrophobic form tohydrophilic ionic form and then back again (or vice-versa). The solventin its hydrophobic form could be miscible with another hydrophobicliquid, and then the solvent could be switched to its hydrophilic ionicform to allow for separation of the resulting two liquid components. Theliquid components may or may not appear as distinct layers. Separationof the components may include decanting, or centrifuging. Afterseparation, it is desirable to convert a hydrophilic ionic form back toits hydrophobic form and water. Because the hydrophobic form isimmiscible with water, it can be separated from the aqueous layer. Thusthe solvent can be reused.

The invention provides a convenient system to control the hydrophilicityof an amidine compound of formula (1) or an amine compound of formula(10), which compounds can each be used as a solvent. Thus, it is usefulin many industrial applications. For example, a chemical reaction thatrequires a hydrophobic solvent could be performed in the switchablesolvent while in its hydrophobic form. Once the reaction is complete,the solvent could be switched to its ionic form which is substantiallyincapable of dissolving the product of the reaction. This would forcethe product to precipitate, if solid, or become immiscible, if liquid.The hydrophilic solvent could then be separated from the product byphysical means such as, for example, filtration or decantation. Thehydrophilic solvent could then be switched back to its hydrophobic formand reused. This method allows the use of a hydrophobic solvent withoutthe requirement for an energy-intensive distillation step to remove thesolvent. Such distillation steps may be complex because both the solventand the product may have similar boiling points.

Switchable solvents of the invention can be useful in water/solventseparations in biphasic chemical reactions. Separation of a hydrophobicliquid from a switchable solvent may be effected by switching theswitchable solvent to its hydrophilic ionic form. This ability toseparate solvents may be useful in many industrial processes where uponcompletion of a reaction, the solvent can be switched to its hydrophilicionic form with the addition of water and a trigger allowing for facileseparation of the two distinct phases. Thus a switchable hydrophilicitysolvent may be used in its hydrophobic form as a medium for a chemicalreaction. Upon completion of the reaction, the chemical product isreadily separated from solution by switching the solvent to itshydrophilic ionic form. The solvent can then be recovered and reused.

In the following Working Examples, two amidines of formula (1),N,N,N′-tributylpentanamidine (BA) and N,N,N′-tripropylbutyramidine (PA),were synthesized in three step procedures. Overall yields for theproducts were typically 22% (BA) and 31% (PA). The amidines werecharacterized by ¹H NMR and ¹³C NMR spectroscopies.

Both BA and PA show hydrophobic behavior, and were converted toamidinium bicarbonates by bubbling CO₂ through an aqueous layer. Thehydrophilic amidinium carbonate forms of both amidines werecharacterized by ¹H NMR and ¹³C NMR spectroscopy. Using information from¹H NMR peak integrations, it was determined that BA behaves reversiblyin hydrophilic switching; when the amidinium bicarbonate solution isheated as described, allowing 89% of the BA to be recovered.

BA was found to be miscible with soybean oil, and was effectively (96%)removed from the oil by only a single wash with carbonated water. Thus,BA is an example of an switchable hydrophilicity solvent of the presentinvention with utility in a new process for extracting oil fromsoybeans.

Initial studies have been conducted to identify applications forswitchable hydrophilicity solvents. These studies are described in theworking examples and include extraction of residual oil from plastic(e.g., polyethylene) containers. These studies are described to providean example of the way that switchable hydrophilicity solvents may beused. Accordingly, amounts of solvent or number of washes are providedas a guide and are not limited to those provided in the workingexamples. In certain cases, less switchable hydrophilicity solvent couldbe used. In other cases more switchable hydrophilicity solvent could beused. Likewise, the number of washings used is intended as a guide.

In the case of plastic containers and residual oil, such oil mayinclude, for example, vegetable oil, petroleum oil, or a combination ofoils. Plastic bottles that are used to house oil are often discardedafter use. Recycling plastic chips made from shredding such containersis difficult due to residual oil that sticks to the plastic. Washingsuch chips with water does not effectively remove the oil, and althoughaddition of surfactant leads to cleaner plastic chips, it makes recoveryof the oil difficult and energy intensive. Accordingly, experiments wereconducted that showed that switchable hydrophilicity solvents wereeffective at cleaning plastic chips and led to recovery of the extractedoil with minimal energy input. See Example 7 for details. In brief,switchable hydrophilicity solvents have the ability to extract residualoil from oil-contaminated plastic such as discarded bottles of engineoil, thus allowing the cleaned plastic to be recycled. Plastic chipwashing can be done in a batch process or a continuous process.Extracted oil can be readily separated from the switchablehydrophilicity solvent by converting the switchable hydrophilicitysolvent, through contact with water and carbon dioxide, to its chargedwater-soluble form. The charged SHS species is changed back into itsneutral form upon removal of carbon dioxide from the system.

Another application for switchable hydrophilicity solvents is its use inconverting mixtures of polystyrene and gas (e.g., foam, extruded foam,expanded foam, foam packing material such as pellets or blocks) intohigh density polystyrene. See Example 8 for full details. Polystyrenefoam (also known as STYROFOAM™) has an air content of about 90%;transporting waste polystyrene foam for recycling is consequently veryenergy intensive. The presence of so much air in the polystyrene foamcan also cause problems in the recycling process itself. Being able toremove the air and then transport and recycle a denser polystyrene isadvantageous. Polystyrene foam treated in this manner can includeexpanded polystyrene foam, extruded polystyrene foam, rigid polystyrenefoam, high impact thin polystyrene, or polystyrene foam packing chips.

As described in the working examples, switchable hydrophilicity solventexhibited the ability to dissolve polystyrene foam quickly. During thedissolution, trapped air from the foam was released as visible bubblesof air which escape the liquid. Addition of a mixture of dissolvedpolystyrene in switchable hydrophilicity solvent to carbonated waterfacilitated precipitation of denser polystyrene. The switchablehydrophilicity solvent switched to its water soluble ionic form uponcontact with water and carbon dioxide. Following separation of thedenser polystyrene, the ionic form was then changed back into itshydrophobic water-immiscible neutral form by removing carbon dioxidefrom the aqueous solution. It was then possible to decant off theswitchable hydrophilicity solvent from the aqueous layer for reuse.

The inventors envision a dissolving unit comprising a vat housing asystem that uses switchable hydrophilicity solvent to dissolve polymerfoam, thereby liberating trapped gas, and then switching the SHS suchthat the polymer precipitates and is collected. Suitable polymeric foamscomprise one or more polymers that are soluble in SHS but that are notsoluble in aqueous solution. Examples of such polymers include expandedpolystyrene foam (EPS), extruded polystyrene foam (XPS), and Styrofoam™.Currently, recycling of such foams is negligible because the economicsof transporting such large volume but lightweight materials isdiscouraging. A dissolving unit of this type could be a portabledissolving unit such as a truck that holds a system that uses SHS. Sucha portable dissolving unit would include means for adding polystyrenefoam into the SHS (e.g., a chipper), and optionally, means for mixing.Mixing may include stirring, shaking or otherwise agitating. In certainembodiments, when a desired concentration of polymeric foam in solventhas been achieved, the contents of the vat could be transferred (e.g.,pumped out) for processing. A pump may be a separate unit or a pump maybe included on the dissolving unit. In other embodiments, the systemcould be equipped to process the mixture. Such units would include meansfor bubbling CO₂ in the presence of water through the liquid mixture ofSHS and dissolved polystyrene to change the liquid mixture into asuspension of hydrophilic (i.e., protonated-SHS) form of the solvent,and solid polystyrene. Such a portable dissolving unit would also havemeans for removal of the solid polystyrene and means for regeneratingthe hydrophobic form of the solvent by heating, degassing and/orflushing with a flushing gas such that the solvent can be used over andover again. In some embodiments, the dissolving unit has a chipper toincrease the surface area of the polymeric foam thereby increasing thedissolution rate of the foam. In some embodiments, the dissolving unithas a stirrer to maintain a consistent concentration throughout thesolvent.

Another application for a switchable hydrophilicity solvent is its usefor extraction of oils from natural feedstocks, such as soybean oil fromsoybeans, algae oil from algae, nut oils from nuts, seed oils fromseeds, vegetable oils from vegetables. Examples include extraction ofcanola oil from canola plants, almond oil from almonds, and hemp seedoil from hemp seed. Such oils may be used for a vast number of usesincluding human or animal consumption, lubricants, and cosmetics.Switchable hydrophilicity solvents may assist with recycling ofmaterials, such as removing the wax coating from milk cartons so thatthe cardboard can be reused. As described in detail in Example 2 usingexemplary switchable hydrophilicity solventN,N,N′-tributylpentanamidine, once hydrophobic soybean oil is extractedfrom soybeans using the uncharged hydrophobic form of the switchablehydrophilicity solvent, the extracted oil can be readily separated fromthe uncharged switchable hydrophilicity solvent by switching theswitchable hydrophilicity solvent to its ionic water-soluble form. Thecharged form of the solvent then partitions into the aqueous phase andthe bean oil can be decanted off from the liquid mixture. Conveniently,the ionic form of the switchable hydrophilicity solvent can be recoveredfor reuse by switching it back into its neutral hydrophobic form byremoving CO₂.

Another application for a switchable hydrophilicity solvent is its useas a medium for biodiesel synthesis. Biodiesel is made from vegetable(e.g., corn, soybean, algae) oil or animal fats. Methods of makingbiodiesel are described in Ma, F. et al. (1999) “Biodiesel Production: areview” Bioresource Technology 70: 1-15. Advantageously, when biodieselis synthesized in a hydrophobic switchable hydrophilicity solventmedium, the biodiesel is miscible in the switchable hydrophilicitysolvent. Thus they are homogeneous single-layer liquid mixture andoptionally, it is possible to separate immiscible by-products. Thenswitchable hydrophilicity solvent can be readily separated from thebiodiesel by extracting the solvent from the biodiesel. Specifically,the switchable hydrophilicity solvent can be switched from its neutralhydrophobic form to its ionic water-soluble form by applying a trigger.An example of such a trigger is an addition of carbonated water. Onceswitched, a two-layer liquid mixture forms since the aqueous solution ofionic form of the switchable hydrophilicity solvent is immiscible withbiodiesel. Once separated, ionic switchable hydrophilicity solvent canbe switched back into its neutral hydrophobic form and reused.

Yet another application for switchable hydrophilicity solvents is itsuse in dissolving and then readily isolating a water-immiscible compoundfrom a mixture. This may include deinking paper to facilitate recyclingof paper including newsprint. It may also include dissolving a selectedpolymer that is in a mixture of reclaimed and recycled material. Forexample, in a mixture of polystyrene and polyethylene, the polystyrenewould dissolve in a liquid comprising a compound of formula (10), butpolyethylene would not dissolve. Thus it would be possible to readilyseparate them, and as described herein, the dissolved polystyrene couldthen be readily separated from the solution by switching the compound toits water-soluble ionic form.

Another example of using a switchable hydrophilicity solvent to dissolveand then isolate a water-immiscible compound from a mixture isextracting biopolymers from their source cells' biomass. One example ofsuch a biopolymer is a family of polyesters is called“polyhydroxyalkanoate” or more simply “PHA”. PHAs are polyesterssynthesized and accumulated by many microorganisms such as Cupriavidusnecator and Pseudomonas putida. Switchable hydrophilicity solvents areexpected to facilitate collection and purification of such biopolymersby selectively dissolving the hydrophobic polymers. Removal of soliddebris is possible via centrifugation to form a supernatant and pelletor via filtration to form a solid and a filtrate. The SHS in thesupernatant or filtrate is then switched to its hydrophilic form bycontacting the liquid with CO₂ in the presence of water. In itshydrophilic form, protonated-SHS migrates to the aqueous layer and asubstantially pure layer of biopolymer forms. Accordingly, thebiopolymer can be collected using, for example, decantation. Optionally,chemical or mechanical mastication of the bacterial cells can be done tobreak open the cell walls and facilitate solubilization of thebiopolymers by the SHS.

Remediation of water contaminated with hydrophobic compound(s) is alsopossible using switchable hydrophilicity solvents. This may includewaste-water, or water used in industrial processes.

Remediation of soil contaminated by a water-immiscible hydrophobicmaterial is also possible using switchable hydrophilicity solvents.Recovery of oil from oil sands, otherwise known as tar sands orbituminous sand, is possible using switchable hydrophilicity solvents.For example, a spill of oil (e.g., petroleum) on soil could be readilydissolved and then regenerated in a clean and usable form without theuse of surfactants, by using switchable hydrophilicity solvents todissolve the oil and leave behind the clean soil, and then the oil couldbe readily separated from the solution by switching the solvent to itsionic form. Other examples of such extraction and then separationinclude hydrophobic material (e.g., oil, drilling fluid) from porousrock, spilled oil from contaminated surfaces, desirable hydrophobiccompounds from biological material (plant or animal), ink from paper,hydrophobic compound from clothing, cleaning of machinery (e.g.,degreasing, removal of lubricants, etc.). In each case, the extractedsubstance can be recovered from the switchable hydrophilicity solvent byswitching the solvent to its water-soluble or water-miscible form.

Another application of switchable hydrophilicity solvents is extractionof oil from drilling fines. Drilling fines are obtained whensubterranean holes are made in search of fossil fuel reserves. Suchfines include rock, sand, soil, water, and oil. Typically, drillingfines are contaminated with up to 40% oil. Prior to development of theswitchable hydrophilicity solvents described herein, such fines weretransported from off-shore drilling platforms to shore by barge. Onceon-shore, fines were stored and oil was removed from the fines bybacterial digestion. This procedure was very costly and time intensive.

Using the switchable hydrophilicity solvents described herein, drillingfines can be cleaned and the contaminant oil readily recovered in ashort period of time.

In some embodiments, drilling fines would be transported to shore andtreated with the SHS to remove the contaminant. This would eliminate theneed for long-term storage.

In other embodiments, treatment of the fines would be done on-site. Aportion of the platform would be used to treat the fines directly on thedrilling platform, which would eliminate the costly transportation andstorage. A system for removing oil from drilling fines would includemeans for washing, mixing and rinsing the fines using a SHS. The rockand sand would then be returned to the site of their removal in a cleanoil-free state. As described herein, contacting the oil-contaminated SHSwith CO₂ in the presence of water would allow for the oil to be readilyseparated from the liquid mixture. The SHS could then be regenerated andseparated from the water by removal of the CO₂ by exposure to air. TheSHS could then be reused in the drilling fines cleaning systemrepeatedly.

Aspects of the present invention may be supplied as a kit. In anembodiment of this aspect, the kit includes a compound of formula (1) ora compound of formula (10) in a suitable container.

For example, suitable containers include simple bottles that may befabricated from glass, organic polymers such as polycarbonate,polystyrene, etc., ceramic, metal or any other material typicallyemployed to hold reagents or food that may include foil-lined interiors,such as aluminum foil or an alloy. Other containers include vials,flasks, and syringes.

Kits may also include instruction materials. Instructions may be printedon paper or other substrates, and/or may be supplied as anelectronic-readable medium, such as a floppy disc, CD-ROM, DVD-ROM, Zipdisc, videotape, audio tape, etc. Detailed instructions may not bephysically associated with the kit; instead, a user may be directed toan internet web site specified by the manufacturer or distributor of thekit, or supplied as electronic mail.

Kits of the invention allow dissolution of a hydrophobic material from amixture and convenient separation of the hydrophobic material asdescribed herein.

WORKING EXAMPLES

The following chemicals were used as received: dibutylamine (98+%,Sigma-Aldrich (“Aldrich”), Oakville, Canada), butylamine (>98%,Aldrich), Nile Red (Aldrich), valoryl chloride (>98%, Fluka, availablefrom Aldrich), dipropylamine (99%, Acros Organics, available throughFischer Scientific), propylamine (98%, Aldrich), butyryl chloride (98%,Aldrich), dimethylsulfate (99.8%, Aldrich), anhydrous diethyl ether(99.9%, Fischer Scientific, Ottawa, Canada), hexane (99.9%, FischerScientific), ethyl acetate (99.9% Fischer Scientific) hydrochloric acid(˜12 M, Fischer Scientific), sodium acetate (Fischer Scientific),potassium hydroxide (Fischer Scientific), triethylamine (≧99%,Sigma-Aldrich), 1,4-dioxane (99+% Aldrich), magnesium sulfate (99.5%+,Alfa Aesar, Ward Hill, USA), HCl in dioxane (˜4 M, Fluka), triethylamine(>99%, Aldrich), N-ethylpiperidine (99%, Aldrich),N,N-dimethylcyclohexylamine (99% Aldrich, also available through AcrosOrganics which are distributed through Fisher Scientific, Pittsburgh,Pa., USA), N,N-diethyl-N-cyclohexylamine (available through Pfaltz &Bauer, distributed through Fisher Scientific, Pittsburgh, Pa., USA),N,N-dimethylhexylamine (98%, Aldrich), N,N-dimethylbutylamine (>98%,Fluka), N,N-diethylbutylamine (97%, Aldrich) methyldipropylamine (98%,Aldrich), N-butylpyrrolidine (98%, Aldrich), trioctylamine (98%,Aldrich), tripropylamine (>98%, Fluka), N,N-dimethyldodecylamine (97%,Aldrich), N,N-diisopropylethylamine (99.5%, Aldrich),N,N-dimethylaniline (99%, Aldrich), methanol-d₄ (99.8+ atom % d,Aldrich), chloroform-d (99.8+ atom % d, Aldrich), D₂O (99.9+ atom % d,Aldrich), DMSO-d₆ (99.9+ atom % d, Cambridge Isotope Labs, St Leonard,Canada), industrial grade RBD (refined, bleached, deodorized) soybeanoil (Bunge, St Louis, USA).

Diethyl ether was purified using a double-column solvent purificationsystem (Innovative Technologies Incorporated, Newbury Port, USA).Compressed gasses were from Praxair (Mississauga, Canada): 4.0 grade CO₂(99.99%) and 5.0 grade Ar (99.999%).

Thin layer chromatography (TLC) was carried out on aluminum-backedsilica gel 60 F₅₂₄ (available from EMD, Gibbstown, N.J., USA). ¹H NMRand ¹³C NMR spectra were collected at 300 K on a Bruker AV-400spectrometer at 400.3 and 100.7 MHz, respectively. IR spectra werecollected on a Thermo Electron Nicolet Avatar 360 FT-IR EnhancedSynchronization Protocol (E.S.P.) instrument (Nicolet InstrumentCorporation, Madison, Wis., USA) between potassium bromide (KBr) plates.Mass spectra were collected on a QStar XL QqTOF (available from AppliedBiosciences/MDS Sciex, Foster City, Calif., USA). Ultraviolet absorbancespectra were collected on an ultraviolet/visible spectrometer withUV-Visible Chemstation software (available from Agilent Technologies,Santa Clara, Calif., USA).

Example 1 Reversible Solvent Switching in an Amidine and Water SystemExample 1A IR and NMR Spectroscopic Characterization of the AmidinesN,N,N′-Tripropylbutyramidine and N,N,N′-Tributylpentanamidine and theirAmidinium Salts

The amidines, N,N,N′-tripropylbutyramidine (PA) andN,N,N′-tributylpentanamidine (BA), can be protonated by carbonic acid,forming N,N,N′-tripropylbutyramidinium bicarbonate (PAB) andN,N,N′-tributylpentanamidinium bicarbonate (BAB). In the presence ofhydrochloric acid, they form N,N,N′-tripropylbutyramidinium chloride(PAC) and N,N,N′-tributylpentanamidinium chloride (BAC).

The ability of both amidines to form salts in the presence of acid wascharacterized. IR spectra of PA and BA were collected by applying a neatsample of the amidines between KBr plates. Chloride (not bicarbonate)salts of both amidines were prepared so that IR spectra of the amidiniumcations could be studied. If the hydrophilic amidinium bicarbonates wereformed, they would revert back to amidines while attempting to removewater, so neat amidinium bicarbonate spectra were not collected.

These salts were formed by dissolving PA or BA (1.0 equivalent) in a 4 MHCl solution in dioxane (2.0 equivalent NCl). The dioxane and excess HClwere removed by vacuum, and the resultant hydrophilic liquid was applieddirectly to KBr plates. The IR spectra of the amidinium chlorides areshown in FIGS. 6B (PAC) and 9B (BAC). These can be compared to the IRspectra of the unprotonated amidines shown in FIGS. 6A (PA) and 9A (BA).In both of the amidinium chloride spectra, the N—H stretch appears as abroad peak in the 3200 cm⁻¹ range.

Based on the changing position of the C═N stretch in IR spectra from1616 cm⁻¹ in the amidines PA and BA to 1626 cm⁻¹ for PAC and 1627 cm⁻¹for BAC, this bond changes strength upon the addition of HCl, whichcorresponds to protonation of the imine nitrogen and delocalization ofthe pi-bond. Also, the introduction of a broad peak at 3200 cm⁻¹suggests the N atom's protonation (N—H stretch).

For comparison to the amidines, ¹H NMR and ¹³C NMR of amidiniumbicarbonates, BAB and PAB, were collected. The samples for these spectrawere prepared by adding preparing two 4 mL vials containing 1 mL D₂O andseveral drops of one amidine to each. The vials were then exposed to CO₂until all traces of amidine disappeared from the water's surface.

The ¹H NMR spectra of PAB and BAB shown in FIGS. 4B and 7B respectivelyshow a significant downfield shift in protons ‘a’ and ‘b’ when comparedto the corresponding protons in PA and BA shown in FIGS. 4A and 7Arespectively. They are deshielded in the protonated form, because thepositive charge introduced by protonation draws electron density fromnearby bonds. The ‘a’ and ‘b’ protons are closest to the amidiniummoieties, so it follows that they should be the most deshielded withreference to their chemical shifts in the amidines. Although the solventused for PA and BA was CDCl₃, while D₂O was used for PAB and BAB, thechanges in chemical shift were not solvent-induced, as they are alsoevident when both amidine forms are dissolved in methanol-d₄.

In the ¹³C NMR spectra, additional peaks were observed in both the PABand BAB spectra of FIGS. 5B and 8B respectively, as compared to PA andBA shown in FIGS. 5A and 8A respectively. Bicarbonate was observed, at160 ppm for PAB and BAB, supporting the hypothesis that the amidines arein their amidinium bicarbonate forms in aqueous solution. Additionally,the number of peaks in the ¹³C NMR spectra, aside from the bicarbonatepeak, has increased by two (to 12) in the case of PAB and by four (to17) in the case of PAB. This suggests increased inequivalence of thealkyl groups on the amine nitrogen, compared to their equivalence in theunprotonated amidine. This observation indicates that the imine nitrogenhas been protonated. The positive charge allows increased contributionfrom the resonance form that previously involved creating formalnegative and positive charges. Now this resonance contributor does notcreate any more charges, but allows the positive charge to delocalize,so it is favored.

Example 1B Qualitative Switchability Assessment forN,N,N′-Tributylpentanamidine

The BA amidine's ability to act as a switchable hydrophilicity solventfor the separation of a selected substance is dependent on its abilityto switch from the hydrophobic form to a hydrophilic form. This isachieved by adding water to provide an aqueous layer and decreasing thepH of the aqueous layer, namely by dissolving CO₂ in the aqueous layer.When carbon dioxide dissolves in water, it forms carbonic acid with pKa₁of 6.4. The resultant dissociation is sufficient to protonate ahydrophobic amidine, causing it to become charged forming a hydrophilicamidinium bicarbonate (BAB). In this preliminary switching study, theamidine's ability to act as a base and its ability to switchhydrophilicity were studied.

Switching behavior was studied for BA over various periods of time. Aglass vial (4 mL) was prepared, containing distilled water (1.0 mL) andBA amidine (0.5 mL).

CO₂ was bubbled through the vial for roughly 30 minutes, until the toplayer had disappeared showing that a hydrophilic solution of BAB inwater had been formed.

A magnetic stirrer was placed in the vial. The vial was suspended in an80° C. oil bath and stirred. The vial was intermittently removed fromthe bath and monitored for the presence of a second layer after 20, 50and 75 minutes. The formation of a second layer (hydrophobic BA) wasnoted after 20 minutes in the oil bath. The volume of the second layerwas found to increase over time. This result showed that the conversionof BA from its hydrophobic form to hydrophilic BAB form was reversiblewith heating.

Example 1C Regeneration of N,N,N′-Tributylpentanamidine (BA) from anAqueous Solution of N,N,N′-Tributylpentanamidinium Bicarbonate (BAB)using Air

In Example 1C, the aqueous solution of BAB was switched back to amixture of BA and water by heating and stirring at 80° C. In thisExample, an alternative method of switching back the BAB is provided.

Switching behavior was studied for an aqueous solution of BAB. A glassvial (4 mL) was prepared, containing distilled water (1.0 mL) and BA(1.0 mL) as a two-phase mixture. CO₂ was bubbled through the vial forroughly 30 minutes, until the top layer had disappeared showing that asingle-phase solution of BAB in water had been formed.

Air was then bubbled through the same glass vial with the single-phasesolution for approximately 5 hours at room temperature to displace CO₂from the solution. The formation of a second layer (hydrophobic BA) wasnoted. This result showed that the conversion of BA from its hydrophobicform to hydrophilic BAB form was reversible by contacting with a gasthat contains substantially no CO₂.

Example 1D Quantitative Switching Study of N,N,N′-Tributylpentanamidine

A methanol-d₄ solution was prepared containing a sodium acetate internalstandard (48.8 mM).

Two 4 mL glass vials containing 1.0 mL D₂O and 0.5 mL BA were preparedand shaken. A 50 μL sample was withdrawn from each layer of one vial andcombined with 0.50 mL of the sodium acetate standard solution in each oftwo NMR tubes: the top layer (BA) in a first tube; the bottom layer(aqueous) in a second tube.

Carbon dioxide was bubbled through the unsampled vial until the BA hadcompletely converted to BAB, as evidenced by the disappearance of thetop layer. The pH of the solution was measured using pH paper to beapproximately 8-9. A 50 μL sample was withdrawn from the BAB/D₂Osolution and added to 0.50 mL of the sodium acetate standard solution ina third NMR tube.

The 4.0 mL vial from which the last NMR sample was withdrawn was thenheated at 80° C. for 1 h and stirred by a magnetic stirrer. Bubbles ofCO₂ were observed escaping from the solution and a top layer,hydrophobic amidine, appeared. After cooling the vial to roomtemperature, a 50 μL sample was withdrawn from each layer and combinedwith 0.50 mL of the sodium acetate standard in two NMR tubes: the toplayer (BA) in a fourth tube; the bottom layer (aqueous) in a fifth tube.

The NMR spectra of all five samples are shown in FIG. 10 with the firstto fifth tubes shown from top to bottom. Although the peakscorresponding to the ‘a’ and ‘b’ protons showed the greatest change inchemical shift upon protonation of the amidine, the other signals wereused for quantitative NMR studies of the switching behavior. This isbecause all appropriate solvents interfered with the ‘a’ protons'signal, while the ‘b’ protons showed a tendency to exchange with proticsolvents, such as methanol-d₄ or the D₂O used in switching experiments.In addition, using the ‘c’ and ‘d’ protons provided stronger signals, toimprove accuracy. Based on the strength of the ‘c’ and ‘d’ signals, 11%of the BA remained in the aqueous phase as BAB after the experiment

Using dioxane as the internal standard gave the same results (11% BABretention in the aqueous phase) as sodium acetate.

The same experiment was repeated except that the temperature of theheating of the 4.0 mL vial was increased from 80° C. to 90° C. A similarretention of BAB in the aqueous phase (12%) was observed.

Example 2 Separation of Bean Oil using Switchable HydrophobicitySolvents N,N,N′-Tributylpentanamidine (BA), N,N-Dimethylcyclohexylamine,or N1,N1,N4,N4-Tetraethylbutane-1,4-Diamine Example 2A Separation ofBean Oil using Switchable Hydrophobicity SolventN,N,N′-Tributylpentanamidine (BA)

A 4 mL vial was prepared containing 1.0 mL D₂O, 0.5 mL BA and 0.5 mLsoybean oil. The vial was shaken thoroughly and allowed to settle,showing a 1.0 mL upper layer (soybean oil and BA) and a 1.0 mL lowerlayer (D₂O). ¹H NMR samples (50 μL) were withdrawn from each layer andmixed with methanol-d₄ (0.5 mL) containing a dioxane internal standard(51.5 mM). Another sample was withdrawn from the upper layer for ¹H NMRanalysis in CDCl₃, because soybean oil is not miscible with methanol.The same volume was discarded from the bottom layer to maintain theinitial ratio.

CO₂ was bubbled through the system for 1.5 h, at which time the toplayer appeared to have halved in volume. Using the same system, ¹H NMRanalysis was again conducted on both layers, the bottom layer inmethanol-d₄ and the top layer in CDCl₃.

A 1.0 mL portion of the bottom layer was withdrawn and transferred to anew 4.0 mL vial. A magnetic stirrer was added and the vial was stirredat 80° C. for 1 h. Samples were withdrawn from both layers for ¹H NMRanalysis in methanol-d₄ with reference to the dioxane internal standard.

The switching behavior of BA in the presence of soybean oil was studiedqualitatively and by ¹H NMR spectroscopy as shown in FIG. 11. The topspectrum is that of soy oil. The middle spectrum is that of the upper(organic) phase after the mixing of the BA, soy oil and D₂O. This upperphase comprises soy oil and BA. The bottom spectrum is that of the upper(organic) phase after the addition of the CO₂ trigger and comprisespredominantly soy oil and any residual solvent.

The most informative ¹H NMR spectra in this experiment were thoseshowing the separation of the soy oil and BA. Based on the integrationof the peak corresponding to BA at 3.17 ppm in these spectra, 96% of theamidine was removed from the upper soybean oil layer after switching toits hydrophilic BAB form. Other spectra (not shown), collected inmethanol-d₄ with a dioxane internal standard, confirmed the switchingbehavior presented in Example 1 above, showing 11% retention of BA inthe aqueous phase after heating.

The soybean oil experiment showed that BA is a switchable hydrophilicitysolvent for soybean oil extraction. BA is miscible with soybean oil andcan be removed by carbonation of the aqueous phase. The amount ofamidine BA removed from the soybean oil may be further improved byincreased time, smaller CO₂ bubbles or agitation. Final traces of theamidine could be removed from soybean oil with an acidic rinse, ifnecessary.

Example 2B Separation of Bean Oil using Switchable HydrophobicitySolvent N,N-Dimethylcyclohexylamine

For this study N,N-dimethylcyclohexylamine, 99%, was purchased fromAcros Chemicals and used as received. Soy flakes were obtained fromBioenterprise Corporation (Guelph, ON, Canada) and used as received.Hexanes (ACS grade) were purchased from Fisher Scientific (Pittsburgh,Pa., USA) and used as received. In order to simulate reverse flowextraction that is employed in industry, extractions were done at lowstir-rates of 200 rpm. Using the same set-up, baseline values wereestablished using hexanes as the solvent.

General Procedure:

To a 100 mL round bottom flask charged with a stir bar was added soybean flakes (5 g). N,N-dimethylcyclohexylamine (30 g) was then added tothe flask and immediately placed in a pre-heated silicone oil bath (25or 60° C.). The extraction was performed for a range of times of 5, 10,15, and 30 minutes, a separated experiment was performed for each timeinterval. Immediately after the timed interval was reached, the flaskwas removed from the oil bath and the contents were suction filteredusing a glass frit until the flakes were dry. The dried flakes were thentransferred to a pre-weighed vial, and the weight of the flakes wasrecorded as mass of oil extracted.

Occasionally, the amine from the oil/amine mixture was removed bysolvent removal using compressed air flow. The resulting oily residuewas characterized by the use of ¹H NMR spectroscopy techniques toconfirm that the extracted soybean oil wasn't altered by the amineduring the extraction process.

Larger Scale Procedure:

To a 500 mL round bottom flask charged with a stir bar was added soybean flakes (50 g). N,N-dimethylcyclohexylamine (300 g) was then addedto the flask and immediately placed in a pre-heated silicone oil bath(60° C.). The extraction was performed for 15, and 30 minutes, aseparated experiment was performed for each time interval. Immediatelyafter the timed interval was reached, the flask was removed from the oilbath and the contents were suction filtered using a glass frit until theflakes were dry. The dried flakes were then transferred to a pre-weighedvial, and the weight of the flakes was recorded as mass of oilextracted. The filtrate (amine/oil mixture) was added to a 10 wt % (toamine) piperazine solution (714 mL), see above for discussion ofpiperazine as a CO₂ absorbption activator. CO₂ was bubbled through thebiphasic mixture for about 45 min. The mixture was allowed to settleafter which the oil was decanted. ¹H NMR spectroscopy techniques wereused to determine the purity of the soy oil.

Effectiveness of SHS for soybean oil extraction was explored at 25° C.and 60° C. and compared to the industry standard of using hexanes at 60°C. An amount of oil extracted was determined at different timeintervals, 5, 10, 15 and 30 min. The solvent/flake mixture was suctionfiltered to remove the solvent/oil and the residue flakes were leftunder suction until dry. The extractions performed at 60° C. reached themaximum amount (within error) of oil extracted within 15 min. When thetemperature was reduced to 25° C. it took at least 30 min to reach asimilar amount of oil extracted as at 60° C. The majority of the oil wasextracted within the first 5 min of the extraction process (25° C.-82%;60° C.-94%), see FIG. 14. Accordingly, best conditions to be used forlarger scale extractions is N,N-dimethylcyclohexylamine at 60° C.Increasing the scale 10-fold shows similar results, the extraction timeincreased slightly to 30 min. The SHS/oil mixture was added to a 10 wt %piperazine solution (relative to SHS). CO₂ gas was bubbled through thebiphasic solution for about 45 min in order to switch the hydrophobicversion of the solvent to its hydrophilic version to extract it from oilinto the water phase. The system was allowed to sit for 24 h and the oilwas decanted. Analysis of the oil by use of ¹H NMR spectroscopytechniques showed an SHS content of 11%.

We have shown that the SHS can be used to efficiently to extract soy oilfrom flaked soy beans. For the soy meal residue to be useful as cow feedand not be a waste product it needs to be free of trace solvents. Thusthe following study was conducted.

Amine Removal from Soy Meal

To determine whether the amine could be removed from the soy mealresulting from the oil extraction procedure, dried soy flakes were addedto an aqueous 10 wt % piperazine solution. The mixture was stirred andCO₂ bubbled through the solution for 3.5 hours. The soy meal wasfiltered through a J-Cloth™ (a loosely woven cloth made for dishwashing)and was squeezed dry. The soy meal was then rinsed with distilled waterand stirred in distilled water for 20 min. The flakes were againfiltered through a J-Cloth™ and rinsed a further 3 times with distilledwater. The flakes were added to a vial, along with a small amount ofd-chloroform and shaken. A ¹H NMR spectrum using d-chloroform as thesolvent was acquired confirming the removal of residual amine on the soymeal after the extraction. This shows that the soy meal can be used as acattle feed stock after extraction of the soy oil using a switchablehydrophilicity solvent, and that it is not a waste product.

Example 2C Separation of Bean Oil using Switchable HydrophobicitySolvent N1,N1,N4,N4-Tetraethylbutane-1,4-Diamine

N1,N1,N4,N4-tetraethylbutane-1,4-diamine was found to be miscible withsoybean oil and can be separated from soybean oil by using carbonatedwater. It was possible to remove a high percentage ofN1,N1,N4,N4-tetraethylbutane-1,4-diamine from the soybean oil be mixingwith carbonated water. The percentage removal was 98.65%. In contrast,96% of BA was removed from the soybean oil. These studies showed thatSHS can replace hexane in soybean oil extraction and eliminateenergy-intensive distillation thereby having advantages in cost, safetyand environmental implications.

Example 3 Polarity Study of N,N,N′-Tributylpentanamidine (BA)

The maximum wavelength of absorption, λ_(max), of a switchablehydrophilicity solvent, N,N,N′-tributylpentanamidine (BA), was analyzedin its hydrophobic and hydrophilic forms using the solvatochromatic dye,Nile Red.

A 1 Dram vial was prepared containing 1 mL of distilled water to which 1mL of BA was added. The contents were stirred at room temperature for 1hour. This ensured saturation of the BA phase with water. The top phasecomprising the BA liquid was pipetted into a quartz cuvette (Semi-MicroCells, Self Masking Black Walls Spectrosil® Quartz, Starna Cells,Atascadero, Calif., USA) and 1 mg of Nile Red was added, to provide abright orange-magenta solution. The ultraviolet absorbance spectrum wasacquired on an Agilent Technologies ultraviolet/visible spectrometer50-60 Hz with UV-Visible Chemstation software. The λ_(max) was 510 nm.

Distilled water (1.0 mL) was then added to the quartz cuvette and carbondioxide was slowly bubbled into the mixture for 1 hour to switch the BAto its ionic form, N,N,N′-tributylpentanamidinium bicarbonate (BAB),after which the homogenous mixture turned purple. The ultravioletabsorbance spectrum of the aqueous solution of the dye and ionic saltwas then acquired as discussed in the previous paragraph. The λ_(max)was 570 nm.

This polarity study shows that the polarity of BA (hydrophobic form) issignificantly lower than that in the aqueous solution of BAB(hydrophilic ionic form). The λ_(max) of 510 nm for water saturated BAindicated that it is quite nonpolar, for example exhibiting a polaritybetween that of diethyl ether and toluene. After switching to the watersoluble ionic form, the dramatic increase in λ_(max) to 570 nm indicatedthat it became significantly more polar, for example exhibiting apolarity greater than ethylene glycol.

Example 4 Synthesis of Amidines N,N,N′-Tripropylbutyramidine (PA) andN,N,N′-Tributylpentanamidine (BA) and AminesN1,N1,N4,N4-Tetraethylbutane-1,4-Diamine and1,1′,1″-(Benzene-1,3,5-Triyl)Tris(N,N-Dimethylmethanamine)

The two amidines N,N,N′-tripropylbutyramidin (PA) andN,N,N′-tributylpentanamidine (BA) were synthesized in the followingthree-step amidine syntheses.

Example 4A Synthesis of N,N-Dibutylpentanamide andN,N-Dipropylbutyramide

N,N-dibutylpentanamide (R=butyl): a round-bottom flask containing amagnetic stirring bar, diethyl ether (400 mL) and N,N-dibutylamine (37mL, 0.22 mol, 2.2 equiv.) was cooled in ice for 30 minutes. Valeroylchloride (12.0 mL, 0.099 mol, 1.0 equiv.) was combined with diethylether (75 mL) and added dropwise over 30 minutes to the stirringdibutylamine solution on ice. A white precipitate, likely the amine'schloride salt, was observed. The flask was removed from ice and stirredat room temperature for 3 h. Two 500 mL extractions were performed withdilute HCI (10 mL conc. HCl per 500 mL extraction) to remove the excessamine and ammonium chloride byproduct. The diethyl ether layer wasretained and dried with MgSO₄. Diethyl ether was removed under rotaryevaporation and high vacuum, leaving crude N,N-dibutylpentanamide.

Rough characterization was performed on the amide via TLC. A solventsystem of hexane:ethyl acetate (80:20 v/v) was prepared. A diethyl ethersolution of the product, N,N-dibutylpentanamide, was applied toaluminum-backed alumina TLC plates. The dibutylamine starting materialwas applied to the plate similarly. The product (amide) appeared with aretention factor of approximately 0.25, while starting material (amine)remained at the origin, as visualized using potassium permanganatesolution. If trace amine remained evident in product, it was removedunder reduced pressure with stirring at 45° C.

The crude amide was then further characterized by ¹H NMR spectroscopybefore proceeding. N,N-dibutylpentanamide results are presented inTable 1. The isolated yield was, 97%, though typical yields for thisreaction range from 94%-99%.

TABLE 1 ¹H NMR spectroscopy peak assignments for N,N-dibutylpentanamideShift (ppm) Multiplicity Integration 3.29 triplet, ³J = 7.6 Hz  4.0 (4)3.20 triplet ³J = 7.7 Hz 2.28 triplet ³J = 7.6 Hz 1.962 (2) 1.4multiplet  12.49 (12) 0.92 multiplet 9.030 (9)

N,N-dipropylbutyramide: a similar procedure implemented withN,N-dipropylamine (2.2 eq) and butyryl chloride (1.0 eq) results in 95%or higher yield of N,N-dipropylbutyramide (R=propyl). It wascharacterized by ¹H NMR spectroscopy a summary of which is presented inTable 2.

TABLE 2 ¹H NMR spectroscopy peak assignments for N,N-dipropylbutyramideShift (ppm) Multiplicity Integration 3.27 triplet ³J = 7.7 Hz  4.0 (4)3.18 triplet ³J = 7.7 Hz 2.27 triplet ³J = 7.5 Hz 1.980 (2) 1.6multiplet 6.268 (6) 0.92 multiplet 9.036 (9)

Example 4B Methylation of N,N-Dibutylpentanamide andN,N-Dipropylbutyramide

Methylation of N,N-dibutylpentanamide (R=butyl): A round-bottom flaskwas prepared, containing N,N-dibutylpentanamide (5.0 g, 0.023 mol, 1.0eq), as synthesized above, and a magnetic stirrer. The flask was fittedto a condenser, flushed with argon and heated to 95° C. Dimethyl sulfate(4.5 mL, 0.046 mol, 2.0 eq.) was added by syringe. The reaction wasmaintained in the 95° C. oil bath under argon for 3 h. After cooling,two diethyl ether washes, 50 mL each, were performed. The diethyl etherlayer took over 30 minutes to become transparent each time and wasallowed to clear before diethyl ether was decanted. Residual diethylether was evaporated.

Methylation of N,N-dipropylbutyramide (R=propyl): a correspondingprocedure was carried out with N,N-dipropylbutyramide (5.0 g, 0.029 mol,1.0 eq) and identical conditions otherwise.

Example 4C Amination to N,N,N′-Tributylpentanamidine andN,N,N′-Tripropylbutyramidine

Amination of N,N,N′-tributylpentanamidine (R=butyl): a round-bottomflask was prepared, containing crude methylated N,N-dibutylpentanamide,as synthesized above, and a magnetic stirrer. Butylamine (7.0 mL, 0.070mol, 3.0 eq) and methanol (40 mL) were added and a condenser wasaffixed. The flask was heated in a 95° C. oil bath (i.e. at reflux) for3 h. After cooling, methanol and excess butylamine were removed viarotary evaporation and high vacuum. The residue was dissolved in 100 mLdistilled water and acidified with 15 mL concentrated HCl. A diethylether wash (100 mL) was performed on the acidic phase to remove residualamide. The aqueous layer was retrieved and basified gradually, usingsolid KOH, until pH paper indicated a pH >11. A thin organic layerformed on top of the aqueous layer as base was added, presumed tocontain amidine, leaving potassium methyl sulfate in the aqueous layer.Diethyl ether (100 mL) was added and dissolved the organic layer. Thediethyl ether layer was retained and dried with MgSO₄. The diethyl etherwas removed via rotary evaporation and high vacuum, leaving crudeN,N,N′-tributylpentanamidine.

As the yield in the methylation step was not determined, the isolatedyield for consecutive methylation and amination was found instead to be23%. This value was typical for N,N,N′-tributylpentanamidine synthesison this scale. The product was characterized by ¹H NMR, ¹³C NMR,electrospray MS and IR spectroscopy.

A ¹H NMR spectrum was acquired for the sample dissolved in CDCl₃ and isshown in FIG. 7A.

A ¹³C NMR spectrum was collected in CDCl₃ and is shown in FIG. 8A.

An electrospray mass spectrum (positive ion mode) was collected, showingthe molecular ion peak (MH⁺) at m/z=269.041, matching the predictedmolecular ion peak for BA.

An infrared spectrum was collected by depositing a drop of neat BAbetween KBr plates and is shown in FIG. 9A. The strong peak at 1616 cm⁻¹was assigned to the C═N double bond stretch.

Amination of N,N,N′-tripropylbutyramidine (R=propyl): the final step wasperformed in the parallel manner for N,N,N′-tripropylbutyramidine fromits methylation product and propylamine (3.0 eq to initial amide).Isolated yield in consecutive methylation/amination was consistentlyhigher than for N,N,N′-tributylpentanamidine, at 32%. The product wascharacterized by ¹H NMR (FIG. 4A), ¹³C NMR (FIG. 5A), electrospray MSand IR spectroscopies (FIG. 6A), in the same manner as BA.

An electrospray mass spectrum (positive ion mode) was collected, showingthe molecular ion peak (MH⁺) at m/z=213.027, matching the predictedmolecular ion peak for PA.

An infrared spectrum (FIG. 6A) was collected by depositing a drop ofneat PA between KBr plates. The strong peak at 1616 cm⁻¹ was assigned tothe C═N double bond stretch.

Example 4D Synthesis of N1, N1,N4,N4-Tetraethylbutane-1,4-Diamine,N,N′-Dipropyl-N,N′-Diethylbutane-1,4-Diamine andN,N,N′,N′-Tetrapropylbutane-1,4-Diamine

N1,N1,N4,N4-tetraethylbutane-1,4-diamine synthesis

N1,N1,N4,N4-tetraethylbutane-1,4-diamine product was synthesized by thereaction of succinyl chloride (1 eq.) and diethylamine (4 eq.) followedby the reduction of diamide with LiAlH₄. A round bottom flask containingdichloromethane (“DCM”) (100 mL) and diethylamine (26.4 g, 35.3 mL,0.361 mol) was maintained under argon atmosphere and cooled in an icebath for 15 min. Succinyl dichloride (12.7 g, 9.2 mL, 0.082 mol) wasadded dropwise as the reaction was exothermic. The reaction mixture wasstirred at room temperature for 3-4 h. The diamide was isolated byadding concentrated HCl (5 mL) and water (150 mL) to separate theammonium salt and unreacted diethylamine in the aqueous layer.Dichloromethane was dried using anhydrous MgSO₄ and was evaporated underreduced pressure using a rotary evaporator to obtain the diamide. Theproduct was characterized by ¹H and ¹³C NMR.

In the second step, LiAlH₄ (159 mL of 2 M solution in tetrahydrofuran(THF)) was added dropwise to the solution of diamide (16.5 g in 50 mL ofdry THF) and maintained at 0° C. under an argon atmosphere. The reactionmixture was refluxed over an oil bath and maintained at 70° C. for 6 h.The extraction of the product from the mixture was performed byquenching the LiAlH₄. In the quenching procedure, for each gram ofLiAlH₄, 1 ml of water was added followed by 1 ml of 15% sodium hydroxideand 5 mL of water.⁵ Then, more THF (100 mL) was added to the mixture. Ifnecessary, the reaction mixture was sonicated for 5 min. The reactionmixture was filtered. The filtrate and washings (30 mL of THF) werepassed through MgSO₄. THF was removed under reduced pressure to obtainN1,N1,N4,N4-tetraethylbutane-1,4-diamine (yield 89%). The product wascharacterized by ¹H and ¹³C NMR spectroscopy and also by high resolutionmass spectroscopy.

Compounds N,N′-dipropyl-N,N′-diethylbutane-1,4-diamine andN,N,N′,N′-tetrapropylbutane-1,4-diamine were made in a similar manner,but using ethylpropylamine or dipropylamine instead of diethylamine tomake the diamide.

Example 4E Synthesis of1,1′,1″-(benzene-1,3,5-triyl)tris(N,N-dimethylmethanamine)

1,1′,1″-(benzene-1,3,5-triyl)tris(N,N-dimethylmethanamine) synthesis

Triamine 1,1′,1″-(benzene-1,3,5-triyl)tris(N,N-dimethylmethanamine) wassynthesized in two steps. The first step of this reaction involved anucleophilic substitution of acyl chloride atoms with nucleophilicnitrogen of dimethylamine. In a round bottom flask, containing amagnetic stir bar, dichloromethane (100 mL) and dimethylamine (54 mL of2.0 M solution in THF), were cooled over an ice bath for 15 minutes andacid chloride (5.0 g, 3.36 mL, 0.018 mol) was added dropwise. Themixture was stirred overnight at room temperature and a light greensolution was obtained. The reaction mixture was evaporated under reducedpressure, to yield a yellow solid. Water (100 mL) was added to thissolid to obtain a clear solution. KOH (3.329 g in 6 mL of water) wasadded to this solution. The resulting solution included an inorganicsalt (KCl), water and NH(CH₃)₂. Water was evaporated under reducedpressure to yield a solid. Methanol (100 mL) was used as solvent todissolve the triamide, while inorganic salt (KCl) remained mostlyundissolved. The methanolic solution was filtered to separate KCl andevaporated under reduced pressure to yield the triamide. The product wascharacterized by ¹H and ¹³C NMR spectroscopy.

In the second step, LiAlH₄ (75.3 mL of 2M solution in THF) was addeddrop wise to the solution of triamide (6.64 g, 0.0228 mol in 50 mL ofdry THF), and maintained at 0° C. under an argon atmosphere. The mixturewas refluxed over an oil bath at 70° C. for 6 h after which, no hydrogenevolution was apparent and the reaction mixture became viscous. Theseparation of the product from the mixture was performed by firstquenching LiAlH₄. In this quenching method, for each gram of LiAlH₄, 1mL of water was added followed by 1 mL of a sodium hydroxide solution(15%) followed by 5 mL of water.⁵ More THF (100 mL) was added and themixture was sonicated for 15 minutes. The product (in THF) was obtainedby filtering this solution to separate it from the white precipitate(oxide/hydroxide of Al). The THF solution (filtrate containing thedesired amine) along with the washings (3×30 mL) were dried overanhydrous MgSO₄ and evaporated under reduced pressure over a rotaryevaporator to obtain the desired1,1′,1″-(benzene-1,3,5-triyl)tris(N,N-dimethylmethanamine) (yield 99%).The product was characterized by ¹H and ¹³C NMR spectroscopy and also byhigh resolution mass spectrometry.

Example 5 Evaluation of the Ability of Amines to Serve as SwitchableHydrophilicity Solvents Example 5A Evaluation of the Miscibility ofAmines with Water in the Absence of CO₂

1 mL of an appropriate amine was combined with 1 mL of H₂O in a 4 mLvial, with the 1 and 2 mL volume lines marked. The vial was manuallyshaken and left to settle at room temperature. After the mixturesettled, the number of phases was observed visually. This procedure wasperformed for all of the screened amines.

The following amines formed a biphasic mixture with water under air:triethylamine,

-   N-ethylpiperidine,-   N,N-dimethylcyclohexylamine,-   N,N-dimethylhexylamine,-   N,N-dimethylbutylamine,-   N,N-diethylbutylamine,-   methyldipropylamine,-   N-butylpyrrolidine,-   trioctylamine,-   tripropylamine,-   N,N-dimethyldodecylamine,-   N,N-diisopropylethylamine,-   N,N-dimethylaniline,-   N1,N1,N4,N4-tetraethylbutane-1,4-diamine,-   1,1′,1″-(benzene-1,3,5-triyl)tris(N,N-dimethylmethanamine,-   1,1′,1″-(cyclohexane-1,3,5-triyl)tris(N,N-dimethylmethanamine,-   N,N′-dipropyl-N,N′-diethylbutane-1,4-diamine,-   N,N,N′,N′-tetrapropylbutane-1,4-diamine.

The following amines formed a single-phase liquid mixture with waterunder air: triethanolamine, N-ethylmorpholine, N-methylpiperidine,N,N,N′,N′,-tetramethylethylenediamine. These water-miscible amines werenot subjected to further experimentation.

Example 5B Evaluation of the Miscibility of Amines with Water in thePresence of CO₂

All of the amines that formed a biphasic mixture in Example 5A weresubjected to the following test. Carbon dioxide was bubbled through theamine/water biphasic mixture, via a syringe needle, for at least onehour. Care was taken to regulate the rate of the CO₂ bubbling, so as notto cause evaporation of the amine. The liquid-liquid interface wasobserved over the course of CO₂ bubbling, and a photo was taken after 60minutes.

The following amines formed a single-phase liquid mixture with waterafter the CO₂ treatment:

-   triethylamine,-   N-ethylpiperidine,-   N,N-dimethylcyclohexylamine,-   N,N-dimethylhexylamine,-   N,N-dimethylbutylamine,-   N,N-diethylbutylamine,-   methyldipropylamine,-   N-butylpyrrolidine,-   1,1′,1″-(benzene-1,3,5-triyl)tris(N,N-dimethylmethanamine,-   1,1′,1″-(cyclohexane-1,3,5-triyl)tris(N,N-dimethylmethanamine,-   N,N′-dipropyl-N,N′-diethylbutane-1,4-diamine,-   N1,N1,N4,N4-tetraethylbutane-1,4-diamine.    These amines are considered switchable hydrophilicity solvents.

The following amines formed a biphasic mixture with water after the CO₂treatment:

-   trioctylamine,-   tripropylamine,-   N,N-dimethyldodecylamine,-   N,N-diisopropylethylamine,-   N,N′,N′-tetrapropylbutane-1,4-diamine, and-   N,N-dimethylaniline.    These amines were rejected and not subjected to further    experimentation.

Example 5C Testing of the Conversion of the Amine SwitchableHydrophilicity Solvents Back to their Hydrophobic Forms

All of the amines identified as switchable hydrophilicity solvents inExample 5B (except N,N-dimethylbutylamine) were subjected to thefollowing test. The vial containing the single-phase amine/water/CO₂mixture prepared in example 5B was heated in an oil bath at 80° C. forapproximately 60 minutes. The mixture was magnetically stirred, andphase separation was observed throughout the course of heating. In thecase of the N1,N1,N4,N4-tetraethylbutane-1,4-diamine/water/CO₂ mixture,5 hours of heating was required to switch it back to its hydrophobicform.

The following amines exhibited loss of amine during this procedure,presumably due to excessive volatility: triethylamine,N,N-diethylbutylamine, methyldipropylamine. In some applications, thisvolatility may be undesired.

Example 5D Converting an Ammonium Bicarbonate Salt to its CorrespondingAmine by Bubbling Air at Room Temperature

A homogeneous aqueous solution of dimethylcyclohexylammonium bicarbonatewas prepared by mixing N,N-dimethylcyclohexylamine (1 mL), and H₂O (1mL) and bubbling with CO₂ for 90 minutes. The 2.0 mL solution was placedin a 10 mL graduated cylinder with a magnetic stir bar and that was thenstoppered with a rubber septum. Air was bubbled through the solution fora total of 28 hours, with constant stirring. After 8 hours, there was noobserved phase separation or volume loss. After an additional 20 hours,a two-phase liquid mixture was observed; its bottom layer wastransparent and colorless, with a volume of 1.6 mL, and its top layerwas clear and slightly oily, with a volume of 0.3 mL. Total volume lossafter 28 hours was 0.1 mL.

Example 6 NMR Spectroscopy of Amine Switchable Hydrophilicity Solvents

The following amines were evaluated in this series of experiments:N-ethylpiperidine, N,N-dimethylcyclohexylamine, andN,N-dimethylhexylamine. The sequence of experiments is described for oneamine but was performed for all three. The visual observations aredescribed in Table 3. 1,4-Dioxane was used as an internal standard forNMR spectroscopy.

Amine (1 mL) was combined with D₂O (1 mL) in a 10 mL graduated cylinder,which was then capped with a rubber septum. The cylinder was manuallyshaken and left to settle at room temperature, after which the mixtureappeared as two transparent liquid phases. For each amine, thisprocedure was simultaneously conducted in 3 identical cylinders. Fromthe aqueous (bottom) layer of one of the three cylinders, three 250 μLsamples were withdrawn, combined with equal volumes of D₂O and dioxaneinternal standard, and analyzed by ¹H NMR spectroscopy. The spectra wereconsistent with the amine in the aqueous phase being in its neutralform. The graduated cylinder from which the samples were taken wasdiscarded.

For each of two remaining graduated cylinders, carbon dioxide wasbubbled through the amine/water biphasic mixture, via a syringe needle,for at least one hour. Care was taken to regulate the rate of the CO₂bubbling, so as not to cause significant evaporation of the amine. Themixture changed from a biphasic liquid mixture to a single homogeneousliquid phase. From one of the two graduated cylinders, a 300 μL sampleof the homogenous liquid phase was withdrawn and mixed with an equalvolume of D₂O and a known quantity of dioxane internal standard. The ¹HNMR spectrum of the mixture showed a shift in the proton signals, whichsuggested that the amine had switched to its protonated, bicarbonatesalt form. The graduated cylinder from which the sample was taken wasdiscarded.

The remaining graduated cylinder, containing the single-phaseamine/water/CO₂ mixture prepared above, was heated in an oil bath at 80deg. C. for 1 hour. Phase separation was observed. Three 250 μL samplesof the aqueous (bottom) layer were withdrawn, combined with equalvolumes of D₂O and a known quantity of dioxane internal standard, andanalyzed by NMR spectroscopy.

TABLE 3 Observations for Example 6 Without CO₂ After CO₂ bubbling Afterheating N-ethyl- formed 2 layers; took 60 min to form after 30 min,separated into 2 piperidine bottom is clear & one clear, pale yellowlayers; bottom is clear, pale colorless, top is homogeneous orange, withvolume of 1 mL, clear & pale yellow, solution. and top is clear yellow,with both with volumes total volume is 1.9 volume of 0.7 mL. NMR of 1 mLmL (loss of 0.1 mL) spectroscopy showed that approximately 49% of theamine remained in the aqueous phase N,N- formed 2 clear, took 45 min toform after 30 min, solution has dimethyl-N- colorless layers, one clear,colorless separated into 2 layers; bottom cyclohexylamine each with 1 mLhomogenous is clear & colorless, with total volume solution. volume of 1mL, and top is no apparent loss of colorless & slightly oily, withvolume volume of 0.8 mL N,N- formed 2 clear, took 75 min to form after30 min solution has dimethyl-N- colorless layers, one clear, colorlessseparated into 2 clear, hexylamine each with 1 mL homogeneous colorlesslayers, bottom is 1 total volume solution. mL, top is 0.9 mL. . NMRtotal volume is 1.9 spectroscopy showed that mL (loss of 0.1 mL)approximately 6% of the amine remained in the aqueous phase.

Example 7 Extraction of Motor Oil from Shredded Plastic Bottles

When plastic bottles of motor oil (vehicle engine lubricant) arediscarded, they contain a significant amount of residual oil. Some suchbottles are made of polyethylene. Current practices of shredding theused bottles into plastic chips for recycling results in oil-coatedplastic chips. Because the oil sticks to the plastic, if the chips arewashed with water, oil remains on the plastic chips. If surfactant isadded to water to wash the chips, separating the water and oil becomesdifficult and energy intensive. Studies were conducted to evaluate theability of switchable hydrophilicity solvents to separate residual oilfrom such plastic chips.

Carbonated water was prepared by bubbling CO₂ through distilled waterfor at least 30 min.

Oil-coated plastic (e.g., polyethylene) chips (70 g) (approximately 1inch diameter) that were obtained from NPI (NexCycle Plastics Inc.) ofBrampton, Ontario, Canada, were placed into a 1 L vessel with a largemagnetic stir bar. N,N-dimethyl-N-cyclohexylamine (210 mL) was added anda lid was placed on the vessel. The contents were stirred for 0.5 h,allowed to sit overnight (˜16 h), and then stirred again for 1 h. Theplastic chips were separated by filtration from homogeneousreddish-brown filtrate (a liquid mixture comprisingN,N-dimethylcyclohexylamine and oil). The plastic chips were washed withcarbonated water (300 mL×2) and distilled water (300 mL×1). The washedplastic chips were left to air-dry resulting in clean, dry plasticchips. Combined washings were added to the filtrate to form a two-layerliquid mixture. As described herein, exposure ofN,N-dimethylcyclohexylamine to CO₂ in the presence of water leads toform ation of its corresponding ammonium salt. The two-layer liquidmixture has an aqueous layer comprising water, CO₂, and some ammoniumsalt and a hydrophobic layer comprising N,N-dimethylcyclohexylamine andoil. CO₂ gas was bubbled through the filtrate liquid mixture with lowagitation to minimize formation of foam. When the amine was protonatedit partitioned out of the hydrophobic layer and into the aqueous layer.After bubbling for several hours the hydrophobic layer comprised thebrown motor oil (7 mL) and only a small amount of residual amine asshown by NMR. The motor oil was decanted and washed with carbonatedwater to remove any residual amine. Washings were not combined with theaqueous layer of the decanted mixture. The aqueous layer was thentreated to a trigger to switch the N,N-dimethylcyclohexyl-ammoniumbicarbonate back to its neutral hydrophobic form. Triggers that wereused included heating to 80° C. (to expel CO₂) in the absence of aflushing gas, and heating to 35° C. while aerating using compressed air.(Aerating with air at room temperature was not effective in thissituation.) Conversion of a substantial portion of thedimethylcyclohexylammonium bicarbonate to N,N-dimethylcyclohexylaminewas confirmed by visual inspection (one aqueous homogeneous solutionbecame two-layers) and by NMR. N,N-dimethylcyclohexylamine, was decantedfrom the aqueous layer and was collected for reuse in this process.

In another study, oil coated plastic chips (˜100g) were placed in a 1 Lvessel, a first washing was performed by addingN,N-dimethylcyclohexylamine (300 mL). The vessel was sealed and itscontents were shaken for 1 minute. The shaking resulted in plastic chipsinterspersed in a liquid mixture of N,N-dimethylcyclohexylamine anddissolved oil. The liquid mixture was then decanted off from the solidplastic chips. The chips were then subjected to a second washing byadding fresh N,N-dimethylcyclohexyl-amine (50 mL) to the vessel housingthe plastic chips and shaking for approximately 10 seconds. This shakingresulted in a liquid mixture and plastic chips. The liquid mixture fromthe second washing was isolated and added to the liquid mixture from thefirst washing. The chips were subjected to a third and a fourth washingby repeating the procedure using fresh N,N-dimethylcyclohexylamine (30mL×2). All of the washings (410 mL of N,N-dimethylcyclohexylamine plus acertain volume of dissolved oil), were then combined with approximately1000 mL of water. This combination appeared as a two layer liquidmixture, where one layer was an aqueous phase, which included the water,and the other layer was a hydrophobic phase, which included theN,N-dimethylcyclohexylamine and the dissolved oil. At this point it wasdesirable to switch the N,N-dimethylcyclohexylamine to its hydrophilicprotonated form, thereby making it have a hydrophilicity sufficient tomigrate away from the hydrophobic phase and into the aqueous phase.Accordingly, the two layer liquid mixture was bubbled for 1-2 hours withCO₂. During the bubbling, it was visually observable that the volume ofthe hydrophobic phase decreased. After the bubbling, a two layer liquidmixture was still observed; however, the hydrophobic layer of the twolayer liquid mixture now was merely comprised of motor oil and a smallamount of residual N,N-dimethylcyclohexylamine solvent, as verified by¹H NMR spectroscopy. The hydrophobic phase comprising motor oil wasdecanted to isolate it from the aqueous phase.

It was then desirable to make the aqueous phase, which appeared as asingle layer liquid mixture and which comprised water and the protonatedform of N,N-dimethylcyclohexylamine, into a two phase liquid mixturewith an aqueous phase, which is water, and a hydrophobic phase, which isN,N-dimethylcyclohexylamine. Accordingly, the aqueous layer, whichcomprised water and the protonated form of N,N-dimethylcyclohexylamine,was then bubbled using compressed air and was heated to about 50 degreesCelcius for several hours until the solvent has returned to itshydrophobic form.

The plastic chips that had undergone five washings as described abovewere subsequently washed with pre-carbonated water (3×500 mL) and water(5×500 mL). The washed plastic chips were dried by blowing compressedair over the chips for several hours followed by allowing them to airdry.

Example 8 Making Higher Density Polystyrene from Polystyrene Foam

Recycling of polystyrene foam is problematic because of its very lowdensity which makes shipping it expensive. Shipping and recycling wouldbe less expensive if it could be converted into a high density form.Studies were conducted that determined that switchable hydrophilicitysolvents could be used to perform this conversion.

Polystyrene foam packing material (e.g., STYROFOAM™) chunks (2 g) weredissolved in 20 mL of N,N-dimethylcyclohexylamine to make a viscous 10wt % liquid mixture. Carbonated water was prepared in a separate vesselby vigorously bubbling distilled water with CO₂ for 30 minutes, and theCO₂ bubbling and vigorous stirring were continued during the experiment.The viscous mixture was then manually into carbonated water (200 mL)injected using a small bore needle. This addition was done slowly (overapproximately 40 min) with vigorous stirring (for high shear) to avoidproducing large clumps of polystyrene with trapped amine, but rather toproduce strings of polystyrene with little to no trapped amine. Thisaddition was performed slowly to allow the N,N-dimethylcyclohexylamineto react with the carbonated water to form its salt form, the salt formbeing water-soluble. Upon addition of the mixture to the carbonatedwater, polystyrene thread-like strands were produced while a substantialportion of the N,N-dimethylcyclohexylamine reacted with the carbonatedwater to form its corresponding water-soluble bicarbonate salt. Thepolystyrene strands were collected by filtration, washed with carbonatedwater and air dried. In these initial studies, small amounts ofN,N-dimethylcyclohexylamine (up to 10%) were attached to the polystyrenestrands, as shown by NMR. Optimization of the precipitation process isexpected to reduce the amount of attached amine, for example, use of anextruder would provide appropriate temperatures to drive off residualamine and water. Using the above-described process, the volume of 2 g ofexpanded polystyrene foam was decreased from 140 cm³ to 2 cm³ of densepolystyrene. This method has also successfully performed using a 40 wt %liquid mixture of polystyrene foam in N,N-dimethylcyclohexylamine.

Example 9 Extraction of Bitumen from Oil Sands

In a fumehood, a sample of oil sands (13.68 g) (obtained from SyncrudeCanada Ltd., Fort McMurray, Alberta, Canada) was placed into a tared 250mL beaker with a cross-shaped stir bar. N,N-Dimethylcyclohexylamine (35mL, 27.36 g, 0.849 g/mL, 2 g per g of oil sands) was measured in a 100mL graduated cylinder and added to the oil sands in the beaker insidethe fumehood. A stir plate was placed under the beaker, turned on andset at 200 rpm. The solution was stirred for an hour. The stir plate wasturned off and the stir bar was removed from the mixture. The solutionwas vacuum filtered using a ceramic Büchner funnel with a filter paper(Fisher Scientific, diameter 9.0 cm). Solids captured in the filter werewashed with N,N-dimethylcyclohexylamine (10 mL) and vacuum was continuedfor an hour. After the vacuum was turned off, the solids were removedfrom the filter and placed into a clean, tared 250 mL beaker. The massof the solids was recorded (11.74 g).

In order to ensure the maximum removal of bitumen from the oil sands,the washing procedure was repeated. Using a 100 mL graduated cylinder,N,N-dimethylcyclohexylamine (27 mL) was measured and added to the solidsin the beaker in a fumehood. The beaker was placed on the stir plate anda cross-shaped stir bar was placed in the beaker. The stir plate wasturned on and set at 200 rpm. The solution was stirred for an hour. Thestir plate was turned off and the stir bar was removed from thesolution. The mixture was vacuum filtered using a Büchner funnel. Thecaptured solids were washed with N,N-dimethylcyclohexylamine (10 mL) andthe vacuum was continued for an hour. After the vacuum was turned off,the solids were removed from the filter and placed into a clean, tared250 mL beaker. The mass of the sand was recorded (11.56 g).

Extraction of Residual Oil from the Cleaned Oil Sands Solids

In a fumehood, using a 100 mL graduated cylinder, toluene (30 mL) wasmeasured and then added to the beaker containing the washed solids fromthe above procedure. The beaker was placed onto a stir plate and across-shaped stir bar was added. The mixture was stirred at 150 rpm forone hour. The stir plate was turned off and the stir bar was removedfrom the mixture. The mixture was vacuum filtered using a Büchnerfunnel, washed with toluene (10 mL) and the vacuum was continued for anhour. After the vacuum was turned off, the solids were removed from thefilter and placed into a clean, tared 30 mL vial. The mass of the sandwas recorded (15.26 g).

The toluene solution was placed into a 100 mL round bottom flask andattached to a rotary evaporator. The toluene was removed by rotaryevaporation, after which the flask contained only an oily residue havinga mass of 18.2 mg. We therefore conclude that the oil sands solids,after the two washes with dimethylcyclohexylamine, contained only 18.2mg of bitumen.

Extraction of Amine from Oil

Based on the total amount of amine (82 mL, 69.92 g, 0.849 g/mL) used towash the oil, a similar amount of distilled water (70 mL) was measuredinto a 100 mL graduated cylinder and placed into a 250 mL Erlenmeyerflask. In a fumehood, the flask was secured to a retort stand and a gasdispersion tube (available as model number 7202-20 from Ace Glass ofVineland, N.J., USA) was placed into the flask. The water was carbonatedby bubbling carbon dioxide through the dispersion tube for an hour at aflow rate of approximately 500 mL/min. A separatory funnel ring wasattached to a retort stand in the fumehood. The carbonated water wasadded to a tared 500 mL separatory funnel. The amine/oil solution fromthe oil sands extraction was also added to the separatory funnel. Thedispersion tube was then placed into the separatory funnel and carbondioxide was bubbled through the solution until the separated oil wasvisibly thick and stuck to the sides of the separatory funnel. Theaqueous phase (lower layer) was then released into a tared 250 mLErlenmeyer flask. The oil was allowed to sit in the separatory funnelovernight. Any amine/water that separated overnight was then releasedinto the same flask the next day.

The separatory funnel was then washed with toluene so that all of theoil was dissolved into the toluene. The toluene solution was thenemptied from the separatory funnel into a tarred 250 mL round bottomflask. The round bottom flask was then placed on a rotary evaporator andthe toluene was evaporated off of the oil. The mass of the residual oilwas then recorded (1.94 g).

Separation of Amine from Aqueous Phase

Distilled water (900 mL) was added to a 1000 mL beaker and placed on astir plate. A cross-shaped stir bar was added to the water. The stirplate was set to heat to a temperature of 60° C. and to stir at 250 rpm.This assembly served as a hot water bath. Using a clamp, the Erlenmeyerflask containing the aqueous phase from the previous procedure was setin the hot water bath and secured to the retort stand. A dispersion tubewas placed into the solution and nitrogen gas was bubbled through thesolution at a flow rate of approximately 500 mL/min. After some time,the liquid contents separated into two liquid phases, the upper(organic) phase was yellow. The lower (aqueous) phase was also initiallyyellow. The solution was kept in the bath at 60° C. and bubbled withnitrogen until the lower phase became colourless, after which the stirplate and nitrogen were turned off. The flask was taken out of the hotwater bath and allowed to cool to room temperature and to sit overnight.The amine phase (top layer) was pipetted off into a clean, tared 250 mLbeaker. Recovered amounts of amine (48.64 g, 70% of the original amount)and the aqueous phase (77.49 g, 111% of the original amount of water)were recorded. Thus, over half of the amine was recovered and some ofthe amine clearly remained in the water (this is evident because themass of the aqueous phase was greater than the original mass of waterused).

Example 10 Extraction of Oil from a Contaminated Rock Sample fromDrilling Fines

A contaminated rock sample of “cuttings” or drilling fines was obtainedfrom Newalta (of Calgary, Alberta, Canada, but this sample originatedfrom an offshore drilling site near Nova Scotia, Canada, where suchsamples are currently transported to mainland and treated in ponds usingmicrobes). Drilling fines samples were cleaned using hexanes, and usingswitchable hydrophilicity solvent. Prior to treatment, the drillingfines appeared as a wet thick mud that clung to the sides of its vesselquite resembling peanut butter. The resultant products of bothtreatments appeared the same and were transparent light yellow liquidand clumps of dry dirt that were lightly packed into glass tubes withair pockets appearing in between the clumps. Although the products weresubstantially the same, the techniques were different. The hexanesmethod required that the solvent be distilled; in contrast, the SHSmethod required no distillation.

Hexanes Method

In a 250 mL beaker, a sample of contaminated rock (25 g) was stirredinto 100 mL of hexanes for 0.5 h. The mixture was vacuum filtered usinga Büchner funnel and the clean rock sample was air-dried over night. Theresulting filtrate was filtered through a Celite bed to remove fineparticles. The clean filtrate was then placed on a rotary evaporator toremove the hexanes. This resulted in a clear, yellow oil, correspondingto 19 wt% of the original rock sample.

SHS Method

In a 60 mL jar, a sample of contaminated rock (5.0 g) was stirred (400rpm) with 30 mL of N,N-dimethylcyclohexylamine for 0.5 h. The resultingmixture was vacuum filtered using a Büchner funnel having 4 layers offilter paper, followed by filtering through a small bed of Celite, toremove any fine particles. The isolated clean rock sample was air-driedover night. The resulting amine/fluid mixture was combined with 60 mL of2 M aqueous (NH₄)₂SO₄ containing 10 wt % piperazine (with respect to theamine) in a 150 mL graduated jar and bubbled with CO₂ (500 mL/min),using a fritted dispersion tube (145-175 μm porosity), for 0.5 h, withstirring. This resulted in 0.86 g of a clear, yellow oil thatcorresponds to 17 wt % of the original sample.

Example 11 Extraction of an Odorous Compound from Plastic

Odorous plastic chips were received from Entropex (Sarnia, Ontario,Canada). The plastic chips were made from shredded plastic bottles. Thebottles previously stored cleaners and detergents. The source of theodour was believed to be limonene.

In a 1 L jar, 400 g of odorous plastic chips were washed with 100 mL ofdimethylcyclohexylamine for 1 min. The chips were filtered throughCelite and washed with an additional 50 mL of dimethylcyclohexylamine.Following this the chips were washed with 200 mL of carbonated water and1 L of distilled water. The resulting chips were placed on paper toweland air-dried.

In preliminary studies the percentage removal of the odorous compound(s)was not quantified. However, it is noted that prior to treatment forremoval of the odorous compounds, exposure to the odorous plastic chipscaused one experimenter to have a headache that lasted for the remainderof the day and evening, while after treatment for removal of the odorouscompound(s), the same experimenter could perceive no odour, and noheadache was experienced.

In this study it was found that the SHS could be used several timesbefore the organic contaminants needed to be removed from the solvent.The process of removing the contaminants was as described for priorexamples (see FIG. 16). Briefly, the contaminated solvent was combinedwith water and exposed to CO₂. After exposure to CO₂ in the presence ofwater, the SHS migrated into the aqueous phase while the organiccontaminant(s) remained insoluble and were then isolated by filtrationor decantation. The aqueous phase was then exposed to air and heatedslightly to remove dissolved CO₂ and was reused for more washing.

Example 12 Addition of Dye to Textile

Switchable hydrophilicity solvents are useful in dyeing of textiles (seeFIG. 20). A dye is added to and solubilized in a hydrophobic-form liquidSHS. Initially, the dye preferentially remains solubilized in thehydrophobic solvent, relative to adhering to the textile. Then, anaqueous solution is added to the solvent and a two layer liquid mixtureis formed. Optionally, the aqueous solution is pre-carbonated (i.e.,includes dissolved CO₂). The dye stays in the hydrophobic layer of thetwo layer mixture. In the situation where the aqueous solution is notpre-carbonated, CO₂ is bubbled through the aqueous liquid mixture. Underthese conditions, and under the conditions of the aqueous solution beingpre-carbonated, the SHS protonates and migrates to the aqueous layer ofthe mixture. The dye is not solubilized by the aqueous layer and haslittle to no hydrophobic solvent remaining. Accordingly, the dye becomesmore and more insoluble and accordingly adheres to the textile. Textileand its adhered dye can be removed from the aqueous liquid and furtherprocessed (e.g., dried).

It will be understood by those skilled in the art that this descriptionis made with reference to the preferred embodiments and that it ispossible to make other embodiments employing the principles of theinvention which fall within its spirit and scope as defined by theclaims appended hereto.

1-126. (canceled)
 127. A composition comprising: (a) water or an aqueousliquid; (b) dissolved CO₂ from a source other than air; and (c) aswitchable hydrophilicity solvent (SHS) that is a diamine, triamine orpolyamine, wherein the SHS reversibly interconverts from awater-miscible, protonated form to a water-immiscible, liquid,unprotonated form when the amount of dissolved CO₂ is insufficient tomaintain the protonated form of the SHS; wherein the dissolved CO₂ canbe removed by exposing the composition to (i) heat, (ii) a flushing gas,(iii) reduced pressure, or (iv) any combination thereof.
 128. Thecomposition of claim 127, wherein the SHS is a diamine.
 129. Thecomposition of claim 128, wherein the diamine in its unprotonated formhas a logP value of greater than 0.9.
 130. The composition of claim 127,wherein the dissolved CO₂ has a partial pressure greater thanatmospheric pressure.
 131. The composition of claim 127, wherein the SHScomprises a compound of formula (10)

that is immiscible with water; where R⁵, R⁶, and Rare each independentlyH; a substituted or unsubstituted C₁ to C₁₀ alkyl group that is linear,branched, or cyclic; a substituted or unsubstituted C_(n)Si_(m) groupwhere n and m are independently a number from 0 to 10 and n+m is anumber from 1 to 10; a substituted or unsubstituted C₅ to C₁₀ arylgroup; a substituted or a substituted or unsubstituted heteroaryl grouphaving 4 to 10 atoms in the aromatic ring; or any combination of R⁵, R⁶,and R⁷, taken together with the nitrogen atom to which they areattached, are joined to form a heterocyclic ring, wherein a substituentis independently alkyl, alkenyl, alkynyl, aryl, aryl halide, heteroaryl,non-aromatic rings, Si(alkyl)₃, Si(alkoxy)₃, halo, alkoxy, amino, ester,amide, amidine, thioether, alkylcarbonate, phosphine, thioester, or acombination thereof, and wherein at least one of R⁵, R⁶, and R⁷ issubstituted with at least one an amino group.
 132. The composition ofclaim 131, wherein the SHS comprises a compound that isEt₂NCH₂CH₂CH₂CH₂NEt₂, EtPrNCH₂CH₂CH₂CH₂NEtPr,N,N′-dipropyl-N,N′-diethylbutane-1,4-diamine, orN1,N1,N4,N4-tetraethylbutane-1,4-diamine.
 133. The composition of claim127, additionally comprising a hydrophobic component that is insolublein the protonated form of the SHS and soluble in the unprotonated formof the SHS.
 134. The composition of claim 133, wherein the hydrophobiccomponent is bitumen, drilling fluid, hydrocarbons, an odorous compound,nut oil, algae oil, seed oil, vegetable oil, canola oil, soybean oil, apolymer, a biopolymer, a polystyrene, a dye, a corrosion inhibitor, asurface stabilizer, a mordant, a preservative, an antioxidant, anenzyme, an antigen, a brightener, a drug or a polymeric foam.
 135. Amethod for separating a hydrophobic substance from a first mixture,comprising: (a) contacting the first mixture with a switchablehydrophilicity solvent (SHS) that is a diamine, triamine or polyamine ina water-immiscible, unprotonated form to produce a second mixturecomprising a solution of the hydrophobic substance in the SHS; (b) ifsolids are present in the first mixture, separating the solution of thehydrophobic substance in the SHS from the solids; (c) treating thesolution of the hydrophobic substance in the SHS with water and CO₂ atan amount sufficient to reversibly switch the water-immiscible,unprotonated form of the SHS to a water-miscible, protonated form toproduce an aqueous solution comprising said water-miscible, protonatedform of the SHS; and (d) separating said aqueous solution from thehydrophobic substance.
 136. The method of claim 135, wherein the SHScomprises a compound of formula (10)

that is immiscible with water; where R⁵, R⁶, and Rare independently H; asubstituted or unsubstituted C₁ to C₁₀ alkyl group that is linear,branched, or cyclic; a substituted or unsubstituted C_(n)Si_(m) groupwhere n and m are independently a number from 0 to 10 and n +m is anumber from 1 to 10; a substituted or unsubstituted C₅ to C₁₀ arylgroup; a substituted or a substituted or unsubstituted heteroaryl grouphaving 4 to 10 atoms in the aromatic ring; or combination of R⁵, R⁶, andR⁷, taken together with the nitrogen atom to which they are attached,are joined to form a heterocyclic ring, wherein a substituent isindependently alkyl, alkenyl, alkynyl, aryl, aryl halide, heteroaryl,non-aromatic rings, Si(alkyl)₃, Si(alkoxy)₃, halo, alkoxy, amino, ester,amide, amidine, thioether, alkylcarbonate, phosphine, thioester, or acombination thereof, and wherein at least one of R⁵, R⁶, and R⁷ issubstituted with an amino group.
 137. The method of claim 136, whereinthe SHS is a diamine.
 138. The method of claim 136, wherein the SHScomprises a compound that is Et₂NCH₂CH₂CH₂CH₂NEt₂,EtPrNCH₂CH₂CH₂CH₂NEtPr, N,N′-dipropyl-N,N′-diethylbutane-1,4-diamine, orN1,N1,N4,N4-tetraethylbutane-1,4-diamine.
 139. The method of claim 135,wherein the CO₂ has a partial pressure greater than atmosphericpressure.
 140. The method of claim 135, wherein the hydrophobicsubstance is bitumen, drilling fluid, hydrocarbons, an odorous compound,nut oil, algae oil, seed oil, vegetable oil, canola oil, soybean oil, apolymer, a biopolymer, a polystyrene, a dye, a corrosion inhibitor, asurface stabilizer, a mordant, a preservative, an antioxidant, anenzyme, an antigen, a brightener, a drug or a polymeric foam.
 141. Amethod of converting a salt to a water-immiscible liquid comprising: (a)providing the composition of claim 127, wherein said protonated form ofthe SHS is a salt of formula (20)

(b) removing CO₂ from the composition to form a mixture comprising waterand a water-immiscible compound of formula (10) (c) allowing the mixtureto separate into an aqueous phase and the water-immiscible liquid,wherein the water-immiscible liquid comprises the compound of formula(10); where E is oxygen; and R⁵, R⁶, and Rare each independently H; asubstituted or unsubstituted C₁ to C₁₀ alkyl group that is linear,branched, or cyclic; a substituted or unsubstituted C_(n)Si_(m) groupwhere n and m are independently a number from 0 to 10 and n+m is anumber from 1 to 10; a substituted or unsubstituted C₅ to C₁₀ arylgroup; a substituted or a substituted or unsubstituted heteroaryl grouphaving 4 to 10 atoms in the aromatic ring; or any combination of R⁵, R⁶,and R⁷, taken together with the nitrogen atom to which they areattached, are joined to form a heterocyclic ring, wherein a substituentis independently alkyl, alkenyl, alkynyl, aryl, aryl halide, heteroaryl,non-aromatic rings, Si(alkyl)₃, Si(alkoxy)₃, halo, alkoxy, amino, ester,amide, amidine, thioether, alkylcarbonate, phosphine, thioester, or acombination thereof, and wherein at least one of R⁵, R⁶, and R⁷ issubstituted with at least one amino group, where the at least one aminogroup is in its protonated form in the compound of formula (20) andunprotonated form in the compound of formula (10).
 142. The method ofclaim 141, wherein removing CO₂ comprises: heating the composition;placing the composition under reduced pressure; contacting thecomposition with a nonreactive gas that contains substantially no CO₂;both heating the composition and contacting the composition with anonreactive gas that contains substantially no CO₂; or both heating thecomposition and placing the composition under reduced pressure.
 143. Themethod of claim 142, wherein the nonreactive gas contains substantiallyno CO₂, CS₂, or COS.
 144. The method of claim 141, wherein the SHS is adiamine.